Implement fallback in codecs lookup on codec opening fail

Currently, if a codec is unable to open, we emit an error.

Issue:
Some codecs fail on the opening step even though ffmpeg reports they're available.
E.g.

• bug https://bugreports.qt.io/browse/QTBUG-121221, hevc codec fails upon opening on old android versions.
• v4l2_m2m codecs on linux

Solution
If the user doesn't set the exact codec type and the codec opening fails, we should fall back to another codec type.

Note
Hw devices are supposed to be handled properly upon the fallback.