Image Block: Improve Text Entry for Long Alt Text

[SiobhyB]

Fixes: #922

gutenberg: WordPress/gutenberg#29670

Description

With this PR, a new AltTextSettings component has been introduced to replace the current TextControl that exists for entering an image's Alt text. This new component makes use of BottomSheet.SubSheet so that users are taken to a new subsheet when entering alt text.

The end goal is to provide a better experience for users who are entering a longer alt text for their images, as the current text entry has limited room/options for scrolling.

How has this been tested?

The general steps for testing, for both iOS and Android, are as follows:

1. Open Image Block settings.
2. Tap Alt Text and confirm that a new sub sheet opens with a text editor.
3. Enter text into editor and tap the back arrow.
4. Confirm that the image's alt text has been correctly updated by viewing the placeholder displayed alongside Alt Text in the settings panel. This can be further verified by saving changes and confirming the alt text has been correctly updated on the web.

As this is a UI change, I have also tested with dark mode enabled and in landscape mode.

Please see Gutenberg PR for additional details, screenshots, and comments.

PR submission checklist:

• I have considered adding unit tests where possible.
• I have considered if this change warrants user-facing release notes more info and have added them to RELEASE-NOTES.txt if necessary.

[peril-wordpress-mobile]

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[guarani]

This looks good! I approved the GB pr here: WordPress/gutenberg#29670 (review)
If no further changes are needed design-wise, I think this is ready to merge (you'll have to add something to the release notes here, too!)

[hypest]

GitHub reports that gutenberg is conflicting, which is not the case. I will update from develop anyway to see if that fixes the issue.

Edit: it did fix the complain, and the diff is still correct (only change to the Gutenberg hash, pointing to WordPress/gutenberg@c508c1b as it needs to so, all good 👍. Will enable "merge when CI green".