Previously GrantedAuthorities had an implicit package tangle because it
was located in ~.core and FactorGrantedAuthority is in ~.core.authority
and FactorGrantedAuthority's authority property was implicitly expected
to be constants found in `GrantedAuthorities`.
This commit moves the constants to the FactorGrantedAuthority which
resolves this tangle. It wasn't initially done because
FactorGrantedAuthority did not exist at that time.
Closes gh-18030
Rob Winch