Add group writeback functionality

[tomasmota]

Fixes #934

Depends on manicminer/hamilton#199

[manicminer]

@tomasmota I'm keen to get this merged, but I am having issues whilst testing. After enabling writeback for a group, it starts to misbehave and certain requests to GET or PATCH the group start to return a 404 or 403. It seems to be reproducible but I am not sure whether it's something we're doing wrong or whether the API is misbehaving.

I'll dig more into this next week, but for now I have pushed some changes including some docs fixups and bumping Hamilton to pull in the casing fixes.

[tomasmota]

Thanks for testing this out. Have you managed to reproduce it just using hamilton?

[tomasmota]

Let me know if there is anything I can do to help troubleshooting this @manicminer

[manicminer]

@tomasmota Thanks, at this time I am still having issues whilst testing. I'll have to unfortunately bump to next week but will spend time digging deeper in the meantime.

[manicminer]

@tomasmota Good news, the earlier issues with spontaneous 40x responses seem to be resolved. After rebasing and tweaking the schema, this is working great. Thanks again for working on this 👍

[manicminer]

Test results

[github-actions]

This functionality has been released in v2.37.0 of the Terraform Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

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