Etsy provider (WIP)

[codemasher]

Types of changes

What types of changes does your code introduce?

• Bugfix (non-breaking change which fixes an issue)
• New OAuth provider
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation fix or enhancement (no code was touched)
• Other (CI, dependencies, etc., please describe)

Checklist:

• I have checked to ensure there aren't other open Issues or Pull Requests for the same update/change
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in downstream modules
• Static analysis and unit tests pass locally with my changes

Further comments

API access pending, cannot verify functionality yet.