Invisible crypto: Verified Identity change notice on composer: part 1.

[BillCarsonFr]

This is a subset of #2492

Adds minimum support for verified identity change warning notice.

Scope

Fix current implementation inconsistency and provide better UX for verified user who are not anymore.

Figma reference

EX: Show violation warning and disable sending
Web: Show the violation warning
Add a FAQ entry for verification violation

Know Limitations

• The banner only shows the Withdraw Verification and not the Go to Profile option (because currently EX doesn't support verifying other users
• EX: Some possible edge cases on the composer if the violation happens in the middle of for example recording an audio (the composer currently has no support for such interruptions)
• There is no distinction between a verification violation caused by the other changing their identity or the current user changing it's identity (see Invisible crypto: Handle Identity Verification violation after we reset our own identity #2691). Same message is sent in both cases
• Web design needs polishing to match the figma (unwanted padding, gradient in dark mode?)

Tasks

• Warn and block sending on verification violation element-x-ios#3679
• feature(crypto): verification violation handling and block sending element-x-android#4126
• feat(crypto): Support verification violation composer banner element-web#29067
• Invisible crypto: Add FAQ entry that explains verification violation #2692