#25339 [Material] Theme-able TextStyles for AlertDialog

To integrate more fully with desktop form-factors like Android tablets and ChromeOS as well as desktop web and desktop OS support, this release builds more support for keyboard and mouse as first class input devices:

#7758 Recommended implementation of combining characters implementation

#27853 Hook up character events and unmodified code points to Android raw key event handling

#27620 Add a keyboard key code generator

#27627 Adding support for logical and physical key events

#6961 Add hover event support to the engine

#24830 Implement hover support for mouse pointers

As widgets are the core way to interact with users in Flutter, this release continues to add features and fixes to the Flutter widget set with particular attention paid to the SliverAppBar:

#26021 Fix SliverAppBar title opacity and test all cases