Writing summaries to file via option

[Onekone]

While using Pint in CI pipelines and Gitlab interface is neat feature*, fact that you have to dump it into file that's not quite human readable (and therefore cannot be read from CI pipeline logs and on non-Ultimate Gitlab instances), is a bit less so

Following PR adds ability to write summaries to a file, potentially in a different format from one used to write the summary to CLI

For example:

$ ./vendor/bin/pint --output-format=gitlab --output-to-file=./codequality.json --test

Outputs result of a scan in Pint's default elaborate printer, while also writing to a file using GitlabReporter

New options are:

• --output-to-file= - additionally write summary into this file. Using this option requires specifying either --output-format or --format

• --output-format= - accepts same values as --format, and if not defined, falls back to --format. If neither is defined, file isn't written into

* In theory, it's Gitlab Ultimate feature. We over here using Community version, which does not quite display Code Quality reports in Gitlab interface