* Create DeltaTextInputClient

* Remove old tests as updateEditingValueWithDeltas is no longer implemented

* fix analyzer

* Update docs

* Make example more general

* Update docs

* Add assert to check that TextInputClient is a DeltaTextInputClient

* Update assert

* More docs

* update

* Clean up docs

* updates

* Update docs

* updates

* Fix test

* add test

* updates

* remove logs

* fix tests

* Address reviewer comments

* Add text_input_utils.dart

* Address reviewer comments