[draft] npm install cleanup

[aoberoi]

Description

Just trying to chip away at some of the warnings on npm install in this project. Hoping to make it a bit less noisy/scary and tidy up.

1. Resolve npm install warning for @types/diff deprecation. Just removed the package. - Related: Fix timeouts for tests and add a test summary to CI jobs #1828

   npm warn deprecated @types/diff@8.0.0: This is a stub types definition. diff provides its own type definitions, so you do not need this installed.

2. Migrates away from unmaintained npm package fantasticon, replaces with @twbs/fantasticon fork, which is maintained.
   • Tested by running npm run compile-icons (which is indirectly included in the postinstall script too), and then previewing the built font (assets/icons/icon-font.woff) on https://fontdrop.info/. The 3 expected glyphs were present at the expected codepoints.
   • This does NOT resolve the npm install warnings I initially was pursuing. The transitive deps of @twbs/fantasticon still generate several warnings

     npm warn deprecated @npmcli/move-file@2.0.1: This functionality has been moved to @npmcli/fs
     npm warn deprecated npmlog@6.0.2: This package is no longer supported.
     npm warn deprecated are-we-there-yet@3.0.1: This package is no longer supported.
     npm warn deprecated glob@7.2.3: Glob versions prior to v9 are no longer supported
     npm warn deprecated glob@8.1.0: Glob versions prior to v9 are no longer supported
     npm warn deprecated gauge@4.0.4: This package is no longer supported.
     npm warn deprecated @xmldom/xmldom@0.7.13: this version is no longer supported, please update to at least 0.8.*

   • A few possibilities to resolve the warnings above:
     1. Land Migrates from ttf2woff2 to wawoff2 dependency twbs/fantasticon#22, which will cut off the transitive chain of older deps.
     2. (Preferred) Enhance the VSCode Extension API to explicitly allow SVGs for the Icon Contribution point. Then simplify the scripts/compile_icons.ts so that it no longer needs to use @twbs/fantasticon. I could propose this to see how far it gets.

There's some other noise in the logs, but I wanted to gauge interest on potential changes before I worked on them:

1. Look into updating the revision of swift-docc-render, and/or eliminating patches, and/or simplifying scripts/update_swift_docc_render.ts. The scariest of warnings comes from the steps in this script:

   49 vulnerabilities (10 low, 23 moderate, 14 high, 2 critical)

2. Try using bin/build_docs within the docs-render repo instead of vue-cli-service (aka@vue/cli-service), which is no longer maintained.
3. To be continued...

Tasks

• Required tests have been written
• Documentation has been updated
• Added an entry to CHANGELOG.md if applicable