Add Craft.cp.announce() and implement for various loading states

[gcamacho079]

Description

Previously, we had live regions that were very localized (i.e., one for element indexes, live regions attached to buttons like the MultiFunctionBtn, etc.). This PR attempts to simplify screen reader announcements for status messages by:

• Adding a method for making screen reader accessible announcements
• Setting a default live region when initializing the control panel (#global-live-region)
• Adding a live region to the Slideout component (in addition to the Modal live region implemented by @i-just)
• Listening for the addition/removal of modal layers and modifying the active live region accordingly; this is important because activating a modal layer hides other layers (including the #global-live-region and contents of previous layers) from assistive technology.

Related issues

Resolves PT-2091, PT-2062, PT-2064, PT-2063, PT-2060, PT-2089, PT-2031

[linear]

PT-2091 “Sign in with a passkey” button shows loading spinner on click but loading state is not announced to screen reader users

[linear]

PT-2062 When clicking the “Add a passkey button” the loading message isn’t conveyed to screen reader users

[linear]

PT-2064 When clicking “Set up” button, loading spinner isn’t announced to screen reader users

[linear]

PT-2063 Status message associated with password reset loading state isn’t announced to screen reader users

[linear]

PT-2060 “Verify” button shows loading spinner on click but loading state is not announced to screen reader users

[linear]

PT-2089 “Download codes” button loading status isn’t conveyed to screen reader users

[linear]

PT-2031 Loading and search complete status messages are not announced

[brianjhanson]

Looks good! It could be useful to split the announce function out from the Craft.cp object, but that's probably for down the road.

[gcamacho079]

Looks good! It could be useful to split the announce function out from the Craft.cp object, but that's probably for down the road.

Thank you for reviewing @brianjhanson. Where do you think it would be best to move it to?

[brianjhanson]

Looks good! It could be useful to split the announce function out from the Craft.cp object, but that's probably for down the road.

Thank you for reviewing @brianjhanson. Where do you think it would be best to move it to?

Excellent question and why I think it's for a separate PR. It would probably make the most sense as a separate package but we don't have any of the infrastructure in place for that yet.