qt: Use QRegularExpression in AddressBookSortFilterProxyModel class

Summary:
Context from https://github.com/bitcoin-core/gui/issues/578:

The most valued benefit will come when migrating to Qt 6, where QRegExp requires usage of an additional Core5Compat module.
Instead, all use cases of QRegExp could be ported to QRegularExpression.

qt , test: Add tests for searching in AddressBookPage dialog

qt: Use QRegularExpression in AddressBookSortFilterProxyModel class

Co-authored-by: João Barbosa <joao.paulo.barbosa@gmail.com>

This is a backport of core#593
Depends on D18176

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D18177