Added YAML support

[imolorhe]

Closes #84

• Added YAML support
• Also updated the DOM rendering bits to use markdown instead of setting the HTML directly, which is a safer approach
• Also slightly improved the demo UI (it didn't look good with black text on black background)
• Also added a bunch of tests

To support YAML (and potentially other formats), I updated the logic to "resolve" tokens before using them. This is important since the YAML grammar/tokens is different from the JSON grammar/tokens (which is very similar to the JSON5 grammar). So we map the tokens from the different grammars to the equivalent token in the "base" grammar (currently this is the JSON grammar tokens but I think we can/should map to some other arbitrary token set which will force us to properly implement the mappings, otherwise additional changes made may work in JSON mode but without proper testing, may not work in YAML mode, if the mappings were not added).

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: f5b1ebfbd76e0dfab13243b7d68d985045aa6936

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

| Name | Type | | ---------------------- | ----- | | codemirror-json-schema | Minor |

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[netlify[bot]]

✅ Deploy Preview for codemirror-json-schema ready!

Name	Link
🔨 Latest commit	f5b1ebfbd76e0dfab13243b7d68d985045aa6936
🔍 Latest deploy log	https://app.netlify.com/sites/codemirror-json-schema/deploys/65d7fb736df40d0008720113
😎 Deploy Preview	https://deploy-preview-85--codemirror-json-schema.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[acao]

oh this is BEAUTIFUL