gui: Drop BanTableModel dependency to ClientModel

Summary:
Break circular dependencies "qt/bantablemodel -> qt/clientmodel -> qt/bantablemodel"

Note that a dependency on QLocale was introduced in D8492. This PR seems to break an implicit include of QLocale, so it needs to be included explicitly.

This is a backport of Core PR18036 [1/2]
Commit https://github.com/bitcoin/bitcoin/pull/18036/commits/61eb058cc10592cfa314ba2209fb370706100e8b

Test Plan: ninja && src/qt/bitcoin-qt

Reviewers: #bitcoin_abc, majcosta

Reviewed By: #bitcoin_abc, majcosta

Differential Revision: https://reviews.bitcoinabc.org/D8696