Code Review bot now reporting all mozlint warnings

[Marco]

The code review bot has been updated a few days ago to report all mozlint warnings (https://bugzilla.mozilla.org/show_bug.cgi?id=1703664).

I think this is a good time to remind everyone that:
- *Error* issues found by the bot will break CI and cause a backout of the patch, so they must be fixed before landing;
- *Warning* issues found by the bot can be ignored as they won't break CI.

The severity of the issues can be found in the Diff Detail section, where all issues are listed. Also, the inline issues are colored in red if they are errors, in yellow if they are warnings.

This example revision shows it all: https://phabricator-dev.allizom.org/D1758.

Thanks!

- Marco.