TextField and last input character should visible on the screen when the cursor is not shown (#74722)

This fixes a subtle bug in the focus traversal that would leave unfocusable FocusTraversalGroup nodes in the list of sorted nodes to be traversed, causing an assert to fire if you nested a FocusTraversalGroup in another one and made its children unfocusable.

* Expose CupertinoModalPopupRoute for state restoration

* Add state restoration test, expose kCupertinoModalBarrierColor

[flutter] throw more specific error messages if a lerp'd type does not conform to Tween API (#74684)

Added constructor parameters to the ReorderableList that were missing from ScrollView. Also replace a lot of doc comments with macro templates to reduce duplication.

This gets away from the extra static map for global key registrations
in favor of the data structures being instance properties of the build
owner. This still allows for semantically-equivalent static access through
the binding (which in turn gives access to the build owner).

This also adds a `BuildOwner.globalKeyCount` getter to get the count
of global keys associated with widgets currently in the tree.

This removes the nullOk parameter from Actions.invoke, and adds an Actions.maybeInvoke function. The difference is that invoke will now always (in debug mode) throw if an enabled action isn't found, and maybeInvoke will return null if an enabled action isn't found. The invoke function can still return null as the result of the invocation, though, so I purposely didn't change the return value to Object from Object?.