Add C++ Bindings

[JasonAtClockwork]

Description of Changes

This adds C++ server bindings (/crate/bindings-cpp) to allow writing C++ 20 modules.

• Emscripten WASM build system integration with CMake
• Macro-based code generation (SPACETIMEDB_TABLE, SPACETIMEDB_REDUCER, etc)
• All SpacetimeDB types supported (primitives, Timestamp, Identity, Uuid, etc)
• Product types via SPACETIMEDB_STRUCT
• Sum types via SPACETIMEDB_ENUM
• Constraints marked with FIELD* macros

API and ABI breaking changes

None

Expected complexity level and risk

2 - Doesn't heavily impact any other areas but is complex macro C++ structure to support a similar developer experience, did have a small impact on init command

Testing

• modules/module-test-cpp - heavily tested every reducer
• modules/benchmarks-cpp - tested through the standalone (~6x faster than C#, ~6x slower than Rust)
• modules/sdk-test-cpp
• modules/sdk-test-procedure-cpp
• modules/sdk-test-view-cpp
• Wrote several test modules myself
• Quickstart smoketest [Currently in progress]
• Write Blackholio C++ server module

[jdetter]

I've tested this at least with the basic quickstart doc and everything seems to be working. I also looked back and did another pass on the comments that I put down - let me know if you need me to take another look at anything.

I have not done a nit-pick review on the code here since there is quite a lot but I have skimmed it and haven't found anything too concerning. I think it would be better to do a UX review when we go through the follow-up docs PRs anyway. Please request my review when those are ready as well.

Thanks Jason, this is great 👍

[gefjon]

I've only looked at the procedure-related stuff in here, but it looks great - much better than I expected, to be honest. Thanks for all your hard work on this!

[joshua-spacetime]

The view code looks correct. sender is a method in the 2.0 rust module api. But as I understand it, this is not meant to be 2.0 compliant. Also this does not include the query builder which will be added separately.

[jdetter]

I reviewed the changes to tools/upgrade-version and the new versioning change, everything looks good here - just a reminder to make sure everything is tested before merging 🙂

Thanks Jason!

[cloutiertyler]

Approving my code owned files. Left one comment.