Change string sort order

[ironage]

This implements option 3 from #6118

• Strings and Binaries are no longer considered equal even if they have the same payload.
• String sort order uses unsigned character values instead of our utf8_compare. This is a user facing breaking change that has been requested by Incorrect special character sorting #2573
• Since the string order has changed, we need to bump the file format because Set<StringData> and Set<Mixed> (with strings) and all string indexes have a new structure.

The first commit in this PR is a cherry-pick of #5662 because otherwise all this will conflict in a difficult way.

☑️ ToDos

• 📝 Changelog update
• 🚦 Tests (or not relevant)
• C-API, if public C++ API changed.

[jedelbo]

@ironage perhaps you can rebase this once we get master merged into next-major. The "delete some obsolete cruft" is now in master.

[jedelbo]

I will make the merge into next-major once we have a new release.

[ironage]

I will leave this as a draft until it is rebased to include #5662. Additionally, we will need server changes to support the new RQL syntax before releasing this. That is tracked in https://jira.mongodb.org/browse/BAAS-20265.

[michael-wb]

@ironage - #5662 was causing build failures and was reverted. I restored the tg/delete-cruft branch, but a new pull request and fixes will be needed to merge those changes again.

[finnschiermer]

LGTM

[jedelbo]

@ironage can this somehow be divided in two: One PR handling the changes to the query system and one handling the changes to the index? The one handling the index should also include upgrade logic and test cases for that. When you write the upgrade tests, you can create the input files and test case on the branch je/upgrade-from-23-tests.

[ironage]

I will split this up. @jedelbo I cannot find the branch je/upgrade-from-23-tests did you push it?

[ironage]

These changes have been broken down and replaced and merged by 3 parts: #6668 #6669 #6670