add level prefix to splitted baseline files

[staabm]

I think it would be helpful if the splitted baseline files would have a "level0-10" prefix.

as a PHPStan end-user people usually don't know which identifier belong to which level and therefore it would be helpful to see lower level errors, which often times when fixed have a high impact on the number of upper level errors

[janedbal]

That is quite opinionated (the levels are IMO too). So I dont think I would implement this. So this falls into the bucket of "customization not possible" (see the idea)

[staabm]

alternatively, maybe the level could be printed into the comment of each baseline?

atm it reads
# total 122 errors

but could read like e.g.
# total 122 errors (level 0)

[janedbal]

# total 122 errors (level 0)

I can imagine that, if you send PR with that, I'll accept it.

[staabm]

level information is not available in phpstan-src