61401 Make scrollbar thickness and radius customizable (cla: yes, f: cupertino, f: material design, framework)

61714 Implement customizable cursor height (cla: yes, f: cupertino, f: material design, framework, waiting for tree to go green)

62052 Update the FlutterLogo colors and gradients (cla: yes, f: cupertino, f: material design, framework, team, waiting for tree to go green)

62164 Updated material and cupertino tests to use the new button classes (cla: yes, f: cupertino, f: material design, framework, waiting for tree to go green)

62317 Fix some broken doc references (cla: yes, f: cupertino, f: material design, framework)