WIP: Update Swift

[NinjaLikesCheez]

Checklist

• Any new parsing code was already published, integrated, and merged into Semgrep. DO NOT MERGE THIS PR BEFORE THE SEMGREP INTEGRATION WORK WAS COMPLETED.
• Change has no security implications (otherwise, ping the security team)

I've opened this MR to update an aging Swift grammer. Semgrep is unable to scan most Swift files I've tried it against (because of things like freestanding #Preview macros).

I'm not fully up to speed on item one on this list, so I've marked this as a WIP until I can figure that piece out (but I'm away from my computer from Saturday for a week - so it may take a while).

Thanks!

[CLAassistant]

All committers have signed the CLA.

[nmote]

Thanks! Marking as draft while you are working on this. Please mark as ready for review once that is the case!

[NinjaLikesCheez]

@nmote No problem! I've followed the guide (although it's a little confusing in place - especially when I've never touched a lot of these technologies!). I'm unsure how to properly test that this will integrate fine with semgrep. Do you have any advice or documentation I could take a look at?

I've been following this: https://semgrep.dev/docs/contributing/updating-a-grammar but of course I can't do the release part - I wanted to verify nothing has broken by updating this grammar first however.

Thanks!