[electrum] hw plugins: include a copy of pinmatrix.py from python-trezor, remove qt4 code

Summary:

https://github.com/trezor/trezor-firmware/blob/3f1d2059ca140788dab8726778f05cedbea20bc4/python/src/trezorlib/qt/pinmatrix.py

I will use this in the trezor (and clones) plugins in a modified form to work with qt6.
Otherwise we would have to ask the trezor devs, who would actually respond,
but also the keepkey and safet lib authors, who would not... to support qt6.

https://github.com/spesmilo/electrum/commit/5d988af18d68e7425beba1962f2df328bb8a8661
https://github.com/spesmilo/electrum/commit/ecf0a5854de72186cab3d07b59993227f56a9212 (without the Qt6 specific API for now)

Test Plan:

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

Open a pin protected Trezor One wallet

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D18338