93161 Revert “Added widgets/AppModel” (team, framework, f: material design, cla: yes, d: api docs, d: examples, waiting for tree to go green, documentation)

93171 [flutter_conductor] Rewrite writeStateToFile to be in an overidable method. (team, cla: yes, waiting for tree to go green)

93173 Bump Gallery version (team, cla: yes)

93174 [web] add image decoder benchmark (team, cla: yes, waiting for tree to go green)

93175 Added SharedAppData to the widgets library (team, framework, f: material design, cla: yes, d: api docs, d: examples, documentation, will affect goldens)