Feature: Support reviewdog filter mode

[ghaiszaher]

What

Support reviewdog's filter mode : https://github.com/reviewdog/reviewdog#filter-mode

Why

Some important ktlint findings do not appear in the PR diff, e.g.

• When a file is moved to another directory and now an import is unnecessary
• When the usage of a class is removed from the file, and now the import is unused
• Needless blank lines is not catched as well for some reason

In above cases, filter-mode=file can be used. In other projects, we could enforce failing even when unrelated findings. are found with filter-mode= nofilter.

How

By adding a new optional input filter_mode with a default value

Note

Tested in a private repo