38916 Update BUILD.gn for package:flutter_test (a: tests, cla: yes, framework)

38920 [flutter_tool] Handle crashes from doctor validators (cla: yes, tool)

38922 Better docs for text (ready to land) (cla: yes, framework, waiting for tree to go green)

38925 [flutter_tool] Only send one crash report per run (cla: yes, tool)

38930 Implement system fonts system channel listener (cla: yes, framework)

38932 Add build warning for non-debug desktop builds (cla: yes, tool)

38936 Fix KeySet (and LogicalKeySet) hashCode calculation (cla: yes, framework)

38979 Adding onEnd callback to implicit animated widgets (a: animation, cla: yes, framework, waiting for tree to go green)