79566 [flutter_tools] use Url path.Context for joining URI (cla: yes, tool, waiting for tree to go green)

79580 [flutter_tools] split cache into API and implementation (cla: yes, tool)

79587 Migrate fingerprint to null safety (a: null-safety, cla: yes, team, tool)

79603 [flutter_tools] split features into 2 libraries, migrate to null safety (cla: yes, tool)

79608 Remove “unnecessary” imports in test/widgets (cla: yes, framework, tool, waiting for tree to go green)

79611 Migrate android_sdk and application_package to null safety (a: null-safety, cla: yes, team, tool, waiting for tree to go green)