feat: add japanese language

[azuryudragon]

Checklist

Please put "X" in the below checkboxes that apply::

• If committing a bugfix, I have tested it in different browsers (Chrome, Firefox, Safari).
• If committing a new feature, I have first submitted an issue (Please note: you are free to open PRs for non-issued features, but opening an issue increases your chance of a successful PR).
• If committing a new feature, I have also written an appropriate test suite for it.

I have tested the following:

• Qalendar component in month mode.
• Qalendar component in week mode.
• Qalendar component in day mode.
• All of the above modes on emulated mobile view.
• Dragging and dropping events.
• Resizing events in day/week modes.
• Clicking events to open event dialog.

This PR solves the following problem**.

add japanese language

[coveralls]

coverage: 94.641% (-0.02%) from 94.664% when pulling c2a4531 on azuryudragon:master into 1a23000 on tomosterlund:master.

[tomosterlund]

Thanks @azuryudragon for opening this PR, and for contributing to this library. This will be available as v3.4.0 in a moment.

[felix-berlin]

🎉 This PR is included in version 3.4.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀