[Keyboard] Add ISO layout for Durgod K320

[nomis]

Description

Add ISO layout for Durgod K320. This is mostly a copy of the ANSI layout but I've fixed the macro to match where the keys are.

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[nomis]

I've had to add a fix for the media keys because these are wrong in the existing ANSI layout.

[spidey3]

Now that #11778 and #11885 have been merged, this PR has merge conflicts.
Can you please rebase, and push again?

[dkjer]

I believe #11778 covers these changes, at this point.

[nomis]

I believe #11778 covers these changes, at this point.

That still has the wrong Fn+F3 and Fn+F4 media keys.

[dkjer]

I believe #11778 covers these changes, at this point.

That still has the wrong Fn+F3 and Fn+F4 media keys.

Thanks for catching that. I updated #11978 with a fix for these media keys