backends/drm: reject output configurations that can't be powered at all
Just disabling pipelines doesn't work, as the outputs are still enabled in that case and will try to present on the disabled pipeline, causing crashes.
This fixes https://crash-reports.kde.org/share/issue/bbe74a0e4b494c929f8f52bca6a0953b
Commit 2 adds some logic to workspace, which disables outputs if there's not enough crtcs to drive all of them
Commit 3 extends that logic to any other errors, and it might be best to keep that one 6.4 only for now as it could potentially disable outputs when not desired