[generator] Support [Obsolete]/[SupportedOSPlatform] attributes for enum members.

[jpobst]

Fixes: #1037

Adds support for [Obsolete]/[ObsoletedOSPlatform] and [SupportedOSPlatform] attributes on enum members.

[SupportedOSPlatform]

The data for [SupportedOSPlatform] comes from the values provided in the enum-mapping file:

// src/Mono.Android/map.csv
E,29,android/media/MediaRecorder$AudioEncoder.OPUS,7,Android.Media.AudioEncoder,Opus,keep,

The 29 is the API in which we added the enum, which becomes [SupportedOSPlatform ("android-29.0")].

[Obsolete]/[ObsoletedOSPlatform]

The data for the "obsolete" attributes comes from the deprecated and deprecated-since attributes on the original field in the api.xml (if it can be found):

<field deprecated='deprecated' deprecated-since='31' api-since='30' final='true' name='BIND_CHOOSER_TARGET_SERVICE' jni-signature='Ljava/lang/String;' static='true' transient='false' type='java.lang.String' type-generic-aware='java.lang.String' value='&quot;android.permission.BIND_CHOOSER_TARGET_SERVICE&quot;' visibility='public' volatile='false' />

This example results in:

// When using classic obsolete attributes:
[global::System.Obsolete("deprecated")]

// When using new obsolete attributes:
[global::System.Runtime.Versioning.ObsoletedOSPlatform("android31.0")]

One wrinkle is we may have obsoleted the field because we want the user to use the enum instead:

<field deprecated='This constant will be removed in the future version. Use Android.App.RecentTaskFlags enum directly instead of this field.' final='true' name='RECENT_IGNORE_UNAVAILABLE' jni-signature='Ljava/lang/String;' static='true' transient='false' type='java.lang.String' type-generic-aware='java.lang.String' value='&quot;android.permission.BIND_CHOOSER_TARGET_SERVICE&quot;' visibility='public' volatile='false' deprecated-since='31' api-since='30' />

We need to detect this message and not obsolete the enum in this case.

[jpobst]

All the examples provided in #1037 appear correct with this PR:

[Register("POST_NOTIFICATIONS", ApiSince=33)]
[SupportedOSPlatform("android33.0")]
public const string PostNotifications = "android.permission.POST_NOTIFICATIONS";

public enum VibrationEffectSupport
{
  [IntDefinition("Android.OS.Vibrator.VibrationEffectSupportUnknown", JniField="android/os/Vibrator.VIBRATION_EFFECT_SUPPORT_UNKNOWN")]
  [SupportedOSPlatform("android30.0")]
  Unknown = 0,
  [IntDefinition("Android.OS.Vibrator.VibrationEffectSupportYes", JniField="android/os/Vibrator.VIBRATION_EFFECT_SUPPORT_YES")]
  [SupportedOSPlatform("android30.0")]
  Yes = 1,
  [IntDefinition("Android.OS.Vibrator.VibrationEffectSupportNo", JniField="android/os/Vibrator.VIBRATION_EFFECT_SUPPORT_NO")]
  [SupportedOSPlatform("android30.0")]
  No = 2
}

[Register("ACTION_POST_CALL", ApiSince=30)]
[SupportedOSPlatform("android30.0")]
public const string ActionPostCall = "android.telecom.action.POST_CALL";

[jonpryor]

One oddity reviewing this PR is that the description doesn't match my expected usage. For example, the description mentions a <field/>, but the field is for a string, which isn't something that is enumified.

I've attempted to update the commit message to "make sense in context".

[generator] Obsolete&SupportedOSPlatform attributes on enum members (#1066)

Fixes: https://github.com/xamarin/java.interop/issues/1037

Adds support for emitting `[Obsolete]`, `[ObsoletedOSPlatform]`, and
`[SupportedOSPlatform]` custom attributes on enum members.

~~ [SupportedOSPlatform] ~~

The data for `[SupportedOSPlatform]` comes from the values provided
in the enum-mapping file (b00e644e), e.g.
[`xamarin-android/src/Mono.Android/map.csv`][0]:

	// src/Mono.Android/map.csv
	E,29,android/media/MediaRecorder$AudioEncoder.OPUS,7,Android.Media.AudioEncoder,Opus,keep,

The `29` is the API in which we added the enum, which becomes
`[SupportedOSPlatform("android-29.0")]`.

~~ [Obsolete] and [ObsoletedOSPlatform] ~~

The data for the "obsolete" attributes comes from the `deprecated`
and `deprecated-since` attributes on the original field in the
`api.xml`, if it can be found.  For example, given:

	<class name="AccessibilityServiceInfo" jni-signature="Landroid/accessibilityservice/AccessibilityServiceInfo;" …>
	    <field
	            deprecated="deprecated"
	            final="true"
	            name="CAPABILITY_CAN_REQUEST_ENHANCED_WEB_ACCESSIBILITY"
	            jni-signature="I"
	            static="true"
	            transient="false"
	            type="int"
	            type-generic-aware="int"
	            value="4"
	            visibility="public"
	            volatile="false"
	            deprecated-since="26"
	    />
	</class>

in combination with these `map.csv` (b00e644e) entries:

	A,0,,0,Android.AccessibilityServices.AccessibilityServiceCapabilities,None,remove,
	E,18,android/accessibilityservice/AccessibilityServiceInfo.CAPABILITY_CAN_REQUEST_ENHANCED_WEB_ACCESSIBILITY,4,Android.AccessibilityServices.AccessibilityServiceCapabilities,CanRequestEnhancedWebAccessibility,remove,

results in:

	/* partial */ enum AccessibilityServiceCapabilities {
	    // When using classic obsolete attributes:
	    [global::System.Obsolete("deprecated")]

	    // When using new obsolete attributes:
	    [global::System.Runtime.Versioning.ObsoletedOSPlatform("android31.0")]
	    CanRequestEnhancedWebAccessibility = 4,
	}

One wrinkle is we may have obsoleted the field because we want the
user to use the enum instead:

	<field
	    deprecated='This constant will be removed in the future version. Use Android.App.RecentTaskFlags enum directly instead of this field.'
	    name='RECENT_IGNORE_UNAVAILABLE'
	    …
	/>

We need to detect this message and not obsolete the enum in this case.

[0]: https://github.com/xamarin/xamarin-android/blob/17213ea184e23a9020451b265fec459558278489/src/Mono.Android/map.csv

[jpobst]

That's fine, I likely pulled some examples from the reported issue, which covered both consts and enums. The consts aspect was fixed in #1038.