Android - Refactor AvaloniaInputConnection

[emmauss]

What does the pull request do?

Rewrite parts of AndroidInputConnection to respond to android input more accurately. This implementation is based on compose's InputConnection implementation.

What is the current behavior?

Our current implementation is compatible with GBoard due to its low use of composition apis. But not with some other keyboards, like SwiftKey, that makes extensive use of text composition and prediction. As such, words were being skipped or misplaced in those keyboards.

What is the updated/expected behavior with this PR?

A command queue is now being used to batch ime edits. Each command corresponds to an ime action that would affect the text buffer, like composition, commit, and selection updates. If a batch edit is active(common for composition keyboard like SwiftKey), only when batch edit ends would updates be run on the buffer.
Commands that are run affect the text buffer directly, and updates are forwarded to TextInputMethodClient immediately.

How was the solution implemented (if it's not obvious)?

Checklist

• Added unit tests (if possible)?
• Added XML documentation to any related classes?
• Consider submitting a PR to https://github.com/AvaloniaUI/avalonia-docs with user documentation

Breaking changes

Obsoletions / Deprecations

Fixed issues

Fixes #16392

[avaloniaui-bot]

You can test this PR using the following package version. 11.2.999-cibuild0050524-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[avaloniaui-bot]

You can test this PR using the following package version. 11.2.999-cibuild0050586-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]