Retain focus and keyboard visibility of SearchTextField after configuration changes

[saryongkang]

What I have done and why Currently, the app opens keyboard after configuration changed even when a user hid the keyboard by tapping back button or 'search' key. Also, position of cursor is not retained after the event. Therefore, I...

• added focusRestorer modifier to retain focus and keyboard keyboard
• added logic to retain focus and keyboard after configuration changed
• added logic to not view keyboard when a user canceled keyboard by tapping back button or 'search' button
• added logic to ignore change of focus and keyboard during configuration changes

Fixes #1033

Considerations

• Need to cache focus flag value during initialization to avoid incorrect modification during initial composition
• Need to ignore focus changes while the activity is changing configurations
• Need to work well with multiple TextFields

Do tests pass?

• [x] Run local tests on DemoDebug variant: ./gradlew testDemoDebug
• [x] Check formatting: ./gradlew --init-script gradle/init.gradle.kts spotlessApply

Is this your first pull request?

• [x] Sign the CLA
• [x] Run ./tools/setup.sh
• [x] Import the code formatting style as explained in the setup script.

[saryongkang]

As per advice from @JolandaVerhoef, before merging this PR, I will wait for Compose Engineers' opinion on this workaround. I will share them code on internal shadow for this issue: https://issuetracker.google.com/192776771

[saryongkang]

I created another repository to highlight this workaround.

Repo: https://github.com/saryongkang/focus-restorable-textfield Screen recording: https://github.com/android/nowinandroid/assets/978709/93beaef7-ba2f-4f35-a6b3-d90ccfc094b7

[Fando]

There are a few issues:

1. The cursor position is not retained after a configuration change
2. IME state is not retained after configuration changes in all cases. Try changing configuration 5 times in a row, and notice the inconsistency. Sometimes IME state would be preserved and sometimes not.

Tested on a physical device, Pixel 6a, Android 13