55012 Even more vm service refactor (cla: yes, tool)

55085 [flutter_tools] check if requireloader is defined (cla: yes, tool, waiting for tree to go green)

55125 prettify the flutter web bootstrap file (cla: yes, tool)

55141 Support tags in testWidgets (a: tests, cla: yes, framework, tool, waiting for tree to go green)

55152 Support tags when running tests from command line (cla: yes, team, tool)

55160 [flutter_tools] refactor Chrome launch logic to remove globals/statics (cla: yes, tool)

55187 [flutter_tools] migrate windows to assemble (cla: yes, tool)

55212 [flutter_tools] fix type error in symbolize (cla: yes, tool, waiting for tree to go green)