94620 Revert “Mixin for slotted RenderObjectWidgets and RenderBox” (team, framework, f: material design, cla: yes, d: api docs, d: examples, documentation)

94632 Reland “Mixin for slotted RenderObjectWidgets and RenderBox (#94077)” (team, framework, f: material design, cla: yes, d: api docs, d: examples, waiting for tree to go green, documentation)

95044 Fix some issues with samples (team, framework, f: material design, f: scrolling, d: api docs, d: examples, waiting for tree to go green, documentation)

95050 Ban sync/async from user facing code (team, tool, framework, a: animation, f: material design, f: scrolling, f: cupertino, d: api docs, d: examples, f: routes, f: gestures, documentation, f: focus)