48755 Revert “[flutter_tools] File system utilities” (cla: yes, tool)

48757 Reland: [flutter_tools] File system utilities (cla: yes, tool)

48759 [flutter_tools] Refactor Environment and FileStore to be context-free (cla: yes, tool)

48761 AppBar Height Fix (cla: yes, f: material design, framework, waiting for tree to go green)

48770 Roll engine 73d2fb374ccb..157772a31597 (4 commits) (autoroller: commit, cla: yes)

48771 [flutter_tools] Clean up build_aot code post assemble migration (cla: yes, tool)

48776 [flutter_tools] Remove context from Artifacts class (cla: yes, tool)