Allow modification of ListTile's horizontalTitleGap, minVerticalPadding, minLeadingWidth

My yearly pass to fix spelling errors in the API dartdocs.

* Fix ListTile assert when layout at zero size #66636

* migrate material to nullsafety

* address review comments

* address review comments

* fix build

The remaining uses of this pattern were all due to wanting to have
the child's slot when `Element.forgetChild()` was called. However,
when that method is called, the child's `slot` value is still valid
in the context of the parent, so the uses can just use `child.slot`.

This is the final round of cleanup from the fallout of #63269

This reverts commit ce40de69.

(this re-applies #64189 by reverting #64249)

This reverts commit 21cfed34.

* (insert|move|remove)ChildRenderObject Deprecation: Step 1

This deprecates the following methods:

* RenderObjectElement.insertChildRenderObject
* RenderObjectElement.moveChildRenderObject
* RenderObjectElement.removeChildRenderObject

...and replaces them with the following methods:

* RenderObjectElement.insertRenderObjectChild
* RenderObjectElement.moveRenderObjectChild
* RenderObjectElement.removeRenderObjectChild

The reason for the deprecation is to provide the `oldSlot` argument to
the `moveRenderObjectChild` method (such an argument was missing from
the now-deprecated `moveChildRenderObject` method) and the `slot`
argument to the `removeRenderObjectChild` method (such an argument was
missing from the now-deprecated `removeChildRenderObject` method). While
no argument was added to `insertRenderObjectChild`, the name change (and
corresponding deprecation) was made to maintain naming parity with the
other two methods.

This initial step does not update or remove any of the `slotToChild`
patterns that exist in the framework. This work is being separated
into two commits in case something needs to be reverted to minimize
the scope of each commit.

See https://github.com/flutter/flutter/issues/63269 for more info

* add language version 2.8 in packages/flutter

* enable non-nullable analyzer flag

* Adds default cursor and/or mouseCursor property to a number of widgets.
* Adds `MaterialStateMouseCurrsor`.

Adds an "autofocus" param to ListTile and its Checkbox, Radio and Switch variants, and passes the given value through to the wrapped InkWell, Switch, etc.

This is important for scenarios like a settings screen, where the first interactable element on a page may be a SwitchListTile, for example.