* added MaterialStateBorderSide.resolveWith

(Partially) Resolves #68596

* responded to comment nits

* reversed changes to text_buttons

* added test confirming compatibility with chips

* added MaterialStateBorderSide test for chip

* added intended usage for MaterialStateXYZ classes

* another docstring update

* corrected error in use case

* made resolvewith samples closures

* refined materialstatecolor example in docstring

* changed nullability in docstring and added null test

* added missing type in test

* fixed another typo in docstrings