feat: add support for merge queues in repository rulesets

[MXfive]

Resolves #1481

---

Before the change?

• Does not support merge queue rules on rulesets.

After the change?

• Supports merge queue rules on rulesets

Pull request checklist

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)

Does this introduce a breaking change?

Please see our docs on breaking changes to help!

• Yes
• No

---

[MXfive]

Waiting for SDK to be released before rebasing and putting for review. Wanted to get some early feedback on:

1. The code, any issues or changes needed? Quite simple following the other code in that context, descriptions copy pasted from upstream API docs verbatim.
2. Testing, I added the block to the only tests I found referencing these rules, though giving incomplete inputs to these blocks does not fail the tests.
   3. Not yet checked where to add docs, will have a look if I have time over the weekend.

[zepeng811]

@MXfive #2359 have been merged, can you help rebase your PR

[MXfive]

@kfcampbell This is ready for review now :)

[joshmyers]

Love to see this go in 🙏

[bsgrigorov]

This would be very useful for us.

[muhlba91]

it would be awesome if this could be merged soon.

[zepeng811]

@kfcampbell @nickfloyd gentle bump, can we get some eyes on this PR please