Add excludes neon formatter

[marcelthole]

Hi,

i have created a NeonExcludes Error Formatter to create a exludes.neon file. This file could be used as a baseline for a higher PHPStan level.
We can upgrade to phpstan level max and create the excludes.neon file. This file should be included and the new code could be validated with the higher level.

[marcelthole]

Maybe i should add different error messages with special characters like #, <, \, \n, 😃, ', ", \n

[ondrejmirtes]

Thank you very much for this! I took this idea and improved on it a bit:

I introduced count property for ignoreErrors records for a single path: 71a5f12

And then improved your error formatter to actually generate the file with count keys: e779a80

This is how a generated files looks like now: 2518159

I will release this feature as 0.11.17, I hope I'll find to write an article about this tomorrow.

[marcelthole]

That's awesome. This looks much better than my version.
I don't know why, but i received some neon format errors with the single line messages. So i have to switched to the multiline version. But with my test code base i didn't get the error with your updated version.

[ondrejmirtes]

Yes, it happened to me to and it was because Symfony output butchered some escaping around < and >. This is how I fixed it: 03f20e6 (Symfony Console uses HTML-like tags for formatting.)

[ondrejmirtes]

I released it and described in this article :) https://medium.com/@ondrejmirtes/phpstans-baseline-feature-lets-you-hold-new-code-to-a-higher-standard-e77d815a5dff