feat: check duplicated values

[ronnnnn]

Overview

Add check command and duplicates sub command to find duplicated values.

Use Case

Large arb file or many arb files make difficult to find duplicated values. To find them easily, add the commands on arb_utils.

Review Points

• Add duplicates command as sub command to make easy to add another commands on check command.
• Add exit function when the command causes error to stop workflow on CI and make check not pass on GitHub.
• To simplify, not check values which contain placeholders and keys which contain special attributes beginning from @@, at first.

[ronnnnn]

@Rodsevich Please review my ideas and codes.

[Rodsevich]

Hey @ronnnnn ! I'll happily do this today. Thanks for the PR!

[ronnnnn]

@Rodsevich Thank you for your reviews and quick response. I update codes and docs from your advices.

[ronnnnn]

I agree with your approach. I'll try to make foundational feature (supporting only duplicated values). Thank you a lot for your advices.