simplify AC:ViewPaths::_prefixes. by making it recursively traversing up the inheritance chain, classes can override local prefixes.
deprecate AbC:Base::parent_prefixes.
rename ::_local_prefixes to ::local_prefixes to state the public attribute.
document the latter.
make ::local_prefixes private, test overriding it and remove documentation for overriding ::_parent_prefixes.
Merge remote-tracking branch 'apotonick/simplify-prefixes'

This is the rebased version of #15026

Closes #15026
Improve CHANGELOG entry
._prefix is private API so we should not recommend to override it
Mark _prefix as nodoc

These methods are private API.
Follow the documentation guideline
Refactoring the code to make consitional return explicit
Following documentation guideline