Suggest command line arguments without quotes

Replace argument suggestion:

    --video-encoder='c2.android.avc.encoder'

by:

    --video-encoder=c2.android.avc.encoder

On Linux, the quotes are interpreted by the shell, but on Windows they
are passed as is.

This was harmless, because even transmitted as is, they were interpreted
by the shell on the device. However, special characters are now
validated since commit bec3321fff4c6dc3b3dbc61fdc6fd98913988a78, making
the command fail.

Fixes #5329 <https://github.com/Genymobile/scrcpy/issues/5329>