[pigeon] Fix style issues in C++ code (flutter#2349)

[pigeon] Fix C++ generator's handling of non-class host APIs (flutter…

…#2270)

Fix for RMS parsing (flutter#2347)

[flutter_markdown] Fix shrinkWrap not taken into account with single …

…child (flutter#2195)

[go_router] Fix a case-sensitive issue with name in version 4.0.0 or …

…later (flutter#2302)

* [go_router] Find a route by name in a case-insensitive

* [go_router] Test GoRouteInformationParser.namedLocation

* [go_router] Update pubspec and CHANGELOG

* [go_router] Add test pattern

* [go_router] Fix test

[go_router_builder] Allow newer versions of analyzer (flutter#2325)

[extension_google_sign_in] Drop old Flutter versions (flutter#2320)

[flutter_template_images] Add iOS app icon assets (flutter#2266)

Adds unnecessary_import to linter ignore list in generated dart tests (…

…flutter#2293)

[pigeon] Adds `unnecessary_import` to linter ignore list for `package…

…:flutter/foundation.dart` (flutter#2290)