79908 Start migrating flutter_tools test src to null safety (team, tool, cla: yes, waiting for tree to go green, a: null-safety)

79911 Migrate tool version to null safety (team, tool, cla: yes, a: null-safety)

79985 Convert some general.shard base tests to null safety (team, tool, cla: yes, waiting for tree to go green, a: null-safety)

80002 Migrate more tool unit tests to null safety (team, tool, cla: yes, waiting for tree to go green, a: null-safety)

80008 Migrate intellij tests and context_test to null safety (team, tool, cla: yes, waiting for tree to go green, a: null-safety)