Add Artist translations for the japanese locale

[neco-nico]

Motivation / Background

This Pull Request has been created to add new locale data for Japanese artists names to this library.

Additional information

I have written the notation based mainly on a database of The Art Library Consortium which aims at supporting studies on art and art-related fields by promoting access to art research resources in Japan.

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one change. Changes that are unrelated should be opened in separate PRs.
• Commit message has a detailed description of what changed and why. If this PR fixes a related issue include it in the commit message. Ex: [Fix #issue-number]
• Tests are added or updated if you fix a bug, refactor something, or add a feature.
• Tests and Rubocop are passing before submitting your proposed changes.

If you're proposing a new generator or locale:

• Double-check the existing generators documentation to make sure the new generator you want to add doesn't already exist.
• You've reviewed and followed the Contributing guidelines.

[neco-nico]

I ran bundle exec rake console to confirm the translations are working as expected.

irb(main):001:0> Faker::Config.locale = :ja
=> :ja
irb(main):002:0> Faker::Artist.name
=> "ドガ"

[thdaraujo]

very nice, thank you!