Further refactor modifier classnames

[hubacekj]

Looking at the modifier classes, I think we could further unify their names instead of attempting to build sentence-like names: .isToolbarAlignedToTop ➡️ .isToolbarAlignTop, etc. The pattern would be:

1. .is<ELEMENT><PROP-NAME><PROP-VALUE> for oneOf prop types, e.g. .isRootColorPrimary,
2. .is<ELEMENT><PROP-NAME> for truthy boolean prop types, e.g. .isRootBlock.

If you agree, I'd do it in a separate PR (or a commit at least) and also document it in part 4.

Originally posted by @adamkudrna in https://github.com/react-ui-org/react-ui/pull/424#discussion_r974374485