Migrate C# ModuleDef to V9

[RReverser]

Description of Changes

This migrates module definition to V9 for C# modules as we're planning to drop V8, and it can't represent some of the new features.

In the process, also improved Debug pretty-printing for the Rust typespace and nested types (to use in future diffs in tests).

• Fixes Migrate C# scheduling to new API #2061.
• Fixes Test coverage - assert that equivalent Rust and C# modules produce the same DescribeModule output #1589.
• Fixes Rewrite C# server modules off V8 to V9 #1948.

API and ABI breaking changes

If this is an API or ABI breaking change, please apply the
corresponding GitHub label.

Expected complexity level and risk

How complicated do you think these changes are? Grade on a scale from 1 to 5,
where 1 is a trivial change, and 5 is a deep-reaching and complex change.

This complexity rating applies not only to the complexity apparent in the diff,
but also to its interactions with existing and future code.

If you answered more than a 2, explain what is complex about the PR,
and what other components it interacts with in potentially concerning ways.

Testing

Describe any testing you've done, and any testing you'd like your reviewers to do,
so that you're confident that all the changes work as expected!

• Write a test you've completed here.
• Write a test you want a reviewer to do here, so they can check it off when they're satisfied.

[RReverser]

Updated this PR to latest definitions. Thanks to #1661 + @coolreader18's #1675, I can verify that I'm now producing correct ModuleDef as it can generate Rust sources from a C# module. Further testing is still blocked by lack of V9 support in the actual runtime - I'm hitting

SpacetimeDB/crates/core/src/host/wasm_common/module_host_actor.rs

Lines 159 to 163 in 71c7722

	_ => {
	return Err(InitializationError::Describe(
	DescribeError::UnimplementedRawModuleDefVersion,
	))
	}

so leaving this PR as a draft.

[kazimuth]

All of this looks good. The codegen changes look sensible and the better debug-formatting Rust-side is a good idea. My big question is whether it would make sense to get rid of the ColumnAttrs bitfield entirely.

[RReverser]

My big question is whether it would make sense to get rid of the ColumnAttrs bitfield entirely.

What would you replace it with?

[kazimuth]

My big question is whether it would make sense to get rid of the ColumnAttrs bitfield entirely.

What would you replace it with?

On the Rust side, we have a data structure listing indexes, a data structure listing constraints, a data structure listing sequences, and that's it. It seems to work fine, but the logic in C# may be structured differently so that that isn't as easy to do. No need to make the change if it's just makework.

[kazimuth]

I have no complaints. I think we should merge this ASAP.