Replace save|restoreWindowGeometry with Qt functions
Summary:
Backport of Core PR11335
Completes T442 and T318
Co-authored-by: Jason B. Cox <contact@jasonbcox.com>
Test Plan: ninja
Reviewers: deadalnix, schancel, #bitcoin_abc
Reviewed By: deadalnix, schancel, #bitcoin_abc
Subscribers: teamcity
Differential Revision: https://reviews.bitcoinabc.org/D1964