Allow window position or size setting to fail

Setting the window position can be denied, as observed in logs from [1]:

    ERROR: Could not set window position: wayland cannot position non-popup windows

Also do not assume window size setting succeeds.

[1] <https://github.com/Genymobile/scrcpy/pull/6772#issuecomment-4344753479>

Refs #6216 comment <https://github.com/Genymobile/scrcpy/pull/6216#issuecomment-3399353701>
PR #6802 <https://github.com/Genymobile/scrcpy/pull/6802>