[electrum] scripted-diff: use some Qt6 enums

Summary:

• QSizePolicy.(\w+) -> QSizePolicy.Policy.$1
• Qt\.(AlignCenter|AlignHCenter|AlignVCenter|AlignLeft|AlignRight|AlignTop|AlignBottom|AlignJustify|AlignBaseline) -> Qt.AlignmentFlag.$1
• QLineEdit.Password -> QLineEdit.EchoMode.Password
• Qt\.(\w+)Focus([^\w]) -> Qt\.FocusPolicy.$1Focus$2

There are a lot more changes required to switch to the Qt6 API, but we don't need to do it all in a single commit thanks to qtpy providing the Qt6 compatibility layer for Qt5
These instances are the ones related to D18338

Depends on D18338

Test Plan:

QT_API=pyqt6 ./electrum-abc
QT_API=pyqt5 ./electrum-abc

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D18339