Rename ambient cache prewarming method

[1ec5]

Renamed -[MGLOfflineStorage putResourceWithUrl:data:modified:expires:etag:mustRevalidate:] to -[MGLOfflineStorage preloadData:forURL:modificationDate:expirationDate:eTag:mustRevalidate:] to conform to Cocoa naming guidelines in Objective-C and Swift API design guidelines in Swift.

/ref #13119
/cc @fabian-guerra @ChrisLoer

[ChrisLoer]

This looks like a great improvement to me, as you can see the names I exposed weren't pre-meditated, they were just reflecting the underlying mbgl-core methods.

cc @LukasPaczos -- although naming guidelines are a little different on Android, something like this change would probably be an improvement there (and keep the two platform SDKs closer together).

[1ec5]

as you can see the names I exposed weren't pre-meditated, they were just reflecting the underlying mbgl-core methods.

Yep, no worries. One thing to note that the new method name follows the “set [value] for [key]” pattern that’s peculiar to Objective-C and Swift. In most other languages, the idiom is “set [key] to [value]” instead.