ci: Enables opt-in wasm CI build for sql-kit

[scottmarchant]

⚠️ This PR is blocked from final testing and merging until dependent PR's are both merged and released. I added issues to the diff that I will resolve once everything is ready to resolve.

Change summary

Added swift wasm as a opt-in CI target, to help prevent future breakages to swift wasm builds.

This PR is part of a larger effort by PassiveLogic to add wasm support to many popular repositories.

Notes

• CI for this won't pass until a future swift-nio version is ready. See details below.

PR Dependencies

The following PR's must be merged before this PR can be merged:

• fix: Fix compiler error found on latest main that breaks wasip1 (wasm) compilation apple/swift-nio#3271 (already merged, waiting for new swift-nio release)
• feat: Adds opt-in only wasm target to vapor CI workflows ci#54
• Resolve issues breaking Swift Wasm builds for sql-kit #190

Testing done

Verified this new workflow functions correctly using a temporary PR that enables the new wasm build.

See https://github.com/PassiveLogic/sql-kit/actions/runs/15886122859/job/44798410586?pr=1

Remaining work

• Run tests on this once all dependent PR's are merged and released.

[scottmarchant]

Note: We need to wait to merge this PR until all dependencies are merged/released. I'll resolve this issue once that is done.

[scottmarchant]

Hi @gwynne, do you know if there is a way for me to trigger CI here to verify my changes work as expected?

[scottmarchant]

Decided to cherry pick this change to #190, so that #190 can be tested for WASM compilation.