Proof of concept for migrating text selection gestures to Intents -> Actions.

Design Doc: https://docs.google.com/document/d/1FWad01h582de4KoWGLL3-lNMmZtQv6PngqCoZEsknBw/edit?usp=sharing&resourcekey=0-WalZf4ph9eHJquYHxB_s4g

Pre-launch Checklist

• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• I read the [Tree Hygiene] wiki page, which explains my responsibilities.
• I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement].
• I signed the [CLA].
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is [test-exempt].
• All existing and new tests are passing.