65766 Adds getter/setter for slider semantics flag. (a: accessibility, cla: yes, framework)

65787 Flutter Stable Framework Cherrypicks 1.20.4 (a: internationalization, cla: yes, d: examples, engine, f: material design, framework, team, tool)

65817 Clarify the docs on what scrollUntilVisible does (a: tests, cla: yes, d: api docs, documentation, framework)

65832 fix issue #55400 PopupMenuButton positions menu incorrectly with nest… (cla: yes, f: material design, framework, waiting for tree to go green)

65857 [flutter] elide semantic information from certain widget spans (cla: yes, framework, waiting for tree to go green)

65861 fix nullability of ScrollMetrics (cla: yes, framework)