Drop `region` usage from `frint` package

Region is a feature mainly found in `frint-react` package. So `frint` package itself doesn't need to have it baked in.

No files or tests are named. Start by searching the frint package for `region` references and checking how the frint-react package relates to them; done means the core frint package no longer has region usage while the stated frint-react behavior remains unaffected.

Written by the indexing model from the issue text.