Construct boolHook and rboolean regex to deal with boolean attributes. Fixes #9129...

Construct boolHook and rboolean regex to deal with boolean attributes. Fixes #9129. Fixes #9123.

- Construct regex for all attributes which are boolean attributes by specification.

  + This allows us to do what users expect with enumerated attributes and allows us to no longer complicate the issue.

  + People are just too confused with passing "true" instead of true when they should, so we won't have to worry about that anymore.

- Modularize code for dealing with boolean attributes into a separate hook to keep attr short and fast.