Add total problems to output and --quiet argument

[mgrachev]

This PR originates from #240.
I decided to add an additional flag to be able not to display verbose information such as "Found n problems".
In #240 PR uses the flag --no-color for this, but I think we should add the additional flag --quiet.

✔ Checklist:

• This PR has been added to CHANGELOG.md (at the top of the list);
• Tests for the changes have been added (for bug fixes / features);
• Docs have been added / updated (for bug fixes / features).

[DDtKey]

It's a good idea to make a separate flag to control additional output 🚀

The only thing I would point out is that this PR adds not only the --quiet flag, but also the additional output itself 😂

[wesleimp]

LGTM 👌

[mgrachev]

The only thing I would point out is that this PR adds not only the --quiet flag, but also the additional output itself 😂

Fixed 😃

[mgrachev]

@dotenv-linter/core Need your approval again 🙂

[DDtKey]

LGTM 🚀