Enhance --queue-ignore-errors to ignore unit parsing errors

[Resonance1584]

Describe the enhancement

Currently queue-ignore-errors allows a run --all to continue if an error occurs during the operation.

Would it be possible to enhance queue-ignore-errors to also ignore units that fail to parse?

Additional context

I think this might be possible if we handle it similarly to queue-exclude-dirs and mark units as excluded in unit_resolver.

There are implications to the report feature, as we would need to explain the exclusion so this likely needs a little more nuance than just reusing the existing exclusion bool.

RFC Not Needed

• I have evaluated the complexity of this enhancement, and I believe it does not require an RFC.

[yhakbar]

@denis256 to incorporate this into #5040