[CPF] Port SVGView to FoundationEssentials

[gn-adin-b]

Summary

• Use FoundationEssentials for WASI builds while leaving other platforms unchanged.
• Parse Wasm XML with pinned Xylem and retain FoundationXML elsewhere.
• Replace Foundation-only SVG parsing helpers with small pure Swift equivalents.

Validation

• swift test
• Swift tools 5.9 fallback manifest
• Clean release Wasm build
• Wasmtime smoke test through DOMParser and SVGParser
• Verified Wasm objects contain no Foundation, FoundationXML, CoreFoundation, or ICU autolinks

[gn-adin-b]

Initially I wanted to separate these in another repo since it's reusable. But, this repo is public and I can't make this thing public without legal approval so this is the best I can do

https://github.com/GoodNotes/FoundationEssentialsExtras

[0xpablo]

Pointing to a specific rev might be an issue with some internal tooling we have about the SPM registry, but since we are not actively using it ATM we can revisit this problem later, hopefully xylem cuts a version soon.

[gn-adin-b]

You're right. I already faced this now

error: Dependencies could not be resolved because package 'svgview' is required using a stable-version but 'svgview' depends on an unstable-version package 'xylem' and 'svgtonotesitems' depends on 'svgview' 0.2.20-goodnotes-foundation-essentials.

[gn-adin-b]

It's a pretty big PR, thanks @0xpablo for reviewing this really quickly!

I'm going to merge this now but feel free to still leave any comments. This won't be live until I merge https://github.com/GoodNotes/GoodNotes-5/pull/62778 anyway