myth protocol: add a MUSIC_TAG_CHANGEIMAGE command

This command will be used by the albumart editor in the music metadata editor
to change the image type of embedded images in a tracks tag. It also makes
sure the cached images get updated properly.

format: MUSIC_TAG_CHANGEIMAGE <hostname> <songid> <oldtype> <newtype>
MythMusic: re-enable the change image type option in the albumart editor

This uses the MUSIC_TAG_CHANGEIMAGE myth protocol command to change the
image type.
myth protocol: MUSIC_TAG_UPDATE_VOLATILE pass the parameters on separate lines

Passing the parameters as a space separated list could cause problems
myth protocol: MUSIC_* commands pass the parameters on separate lines

Passing the parameters as a space separated list could cause problems
Merge remote-tracking branch 'upstream/master'
Silence a couple of compiler warnings
Make the naming of the 'raw' TS file(s) more predictable.  Make raw TS capture a noop under windows and mingw.

Refs [b0aa4e50c].
Updated Greek MythFrontend, MythMusic and MythBrowser translation
from Yianni Vidalis

Thank you Yianni!

Closes #12094

Signed-off-by: Nicolas Riendeau <nriendeau@mythtv.org>
Merge remote-tracking branch 'upstream/master'