fixed mat2xc alignment in spv

[39ali]

Connections
#9011

Description
fix mat2xc alignment issues in spv when using uniforms, fix issues with uniform array as well

Testing
Explain how this change is tested.

Squash or Rebase?
either

Checklist

• Run cargo fmt.
• Run taplo format.
• Run cargo clippy --tests. If applicable, add:
  • --target wasm32-unknown-unknown
• Run cargo xtask test to run tests.
• If this contains user-facing changes, add a CHANGELOG.md entry.

[ErichDonGubler]

There are no tests, here, but if we need a fix, we need tests, too! Will you please add some tests (preferably snapshot tests emitting the "wrong" code from before) and then amend the current commit to add the snapshot changes?

[ErichDonGubler]

This also needs a CHANGELOG entry.

[39ali]

@ErichDonGubler i did the changes, i can't have an old snapshot because naga would crash

[cwfitzgerald]

Could you explain what this fix is actually doing, I'm not sure I understand it

[39ali]

@cwfitzgerald
it checks to see if a sub-element (like an array index or a struct member) actually needs conversion, before
the code have been blindly attempting to call a conversion function for every element. the conversion function should only be called if a mapping for that specific type exists in std140_compat_uniform_types.
tldr :

• check if the type is marked as needing std140 compatibility.

• loop through the elements (of an array or struct).

• for each element, see if it also needs a layout fix.

• If yes, emit a FunctionCall to the conversion helper. If no, use the ID as-is.

and lastly create a new object that is aligned correctly.

[inner-daemons]

I'm gonna unassign myself since I'm not too familiar with this part of the codebase. Up to you @cwfitzgerald.