61766 [flutter_tools] Add plumbing for widget cache (cla: yes, tool)

61773 Update framePolicy docs (a: tests, cla: yes, d: api docs, documentation, framework, waiting for tree to go green)

61778 [Material] Updated icons and fonts (cla: yes, f: material design, framework, team, tool, waiting for tree to go green)

61779 Add a test for 3D transform with needsCompositing (cla: yes, framework, waiting for tree to go green)

61796 Improved docs for minLines in EditableText (a: text input, cla: yes, d: api docs, documentation, framework, waiting for tree to go green)

61800 re-Update engine hash for 1.20.0-7.2.pre, including 12847e8 (CQ+1, cla: yes, engine)