In native iOS, users are able to select text and initiate a share menu, which provides several standard services, such as copy, sharing to social media, direct ability to send to various contacts through messaging apps, etc. 

https://github.com/flutter/engine/assets/36148254/d0af7034-31fd-412e-8636-a06bbff54765

This PR is the framework portion of the changes that will allow Share to be implemented.
The corresponding merged engine PR is [here](https://github.com/flutter/engine/pull/44554)
This PR addresses https://github.com/flutter/flutter/issues/107578
More details are available in this [design doc](https://github.com/flutter/engine/pull/flutter.dev/go/add-missing-features-to-selection-controls)