* Pulled `FinderBase` out of `Finder`
* `FinderBase` can be used for any object, not just elements
* Terminology was updated to be more "find" related
* Re-implemented `Finder` using `FinderBase<Element>`
* Backwards compatibility maintained with `_LegacyFinderMixin`
* Introduced base classes for SemanticsNode finders
* Introduced basic SemanticsNode finders through `find.semantics`
* Updated some relevant matchers to make use of the more generic `FinderBase`
Closes#123634Closes#115874