[SS-103] Fix COPY FROM PARQUET unsorted map keys

[def-]

Fixes https://github.com/MaterializeInc/database-issues/issues/11290
Updates ColReader::Map logic to sort keys when reading in data.

[github-actions]

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[patrickwwbutler]

Had to update the checks in the test you created - it appears MZ doesn't support the equality operator for maps (at least string maps): ERROR: operator does not exist: map[text=>text] = map[text=>text]

[patrickwwbutler]

feels a bit suspicious reviewing my own changes so I won't merge, but I'm fairly confident this is good to go - also tested without the sort changes and the TD fails as expected

[def-]

The fix looks reasonable to me!

[martykulma]

Nice! The reasoning for the sort needs to be documented in the source, but lgtm otherwise.

🦈

[martykulma]

This is a great clarifying comment about the sort - definitely ought to be in the source!

[ublubu]

👍 It'd be nice to (also) have it on the doc comment for Datum::Map (and/or push_dict_with?) if that type is never supposed to be constructed from unsorted values.

[ublubu]

I see it's already on push_dict_with:

materialize/src/repr/src/row.rs

Lines 2349 to 2351 in 15f2490

	/// The closure **must** push keys in ascending order, otherwise equality
	/// checks on the resulting `Row` may be wrong and reading the dict IN DEBUG
	/// MODE will cause a panic.

[def-]

I'd be even happier if we can get rid of that foot gun. Seems way too easy to use wrongly.