feat: source records nameless match spec

[baszalmstra]

Description

This PR adds additional matchspec fields to the source record to allow distinguishing between multiple outputs with the same package name. This is not (yet) exposed to the user but is required for pin_subpackage to work correctly. This also introduces changes the to pixi-build-types but they should be backwards and forward compatible.

Now that Im breaking the API I also:

• I also fixed casing issues.
• Streamlined the use of directory vs dir.
• Support for pin_compatible.
• Generating a json schema using schemars for the project model and verifying it doesnt change through tests.
• Removed the V1 suffix from all types, this is already captured by the api-version.
• Added build_string and build_number to the project model.

Fixes #4599

How Has This Been Tested?

Not yet, I also need to test this together with a backend that supports this.

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added sufficient tests to cover my changes.
• I have verified that changes that would impact the JSON schema have been made in schema/model.py.

[baszalmstra]

Apparently this change does require a pixi build api version bump. I will check how I can make this more backwards compatible.

[baszalmstra]

Did a self review.