Migrate to js-yaml also in v2, remove yaml.js from dependencies

[generalmimon]

See #166 (comment) (cc @GreyCat)

#165 discusses switching to js-yaml from yaml.js that we had been using. This was addressed in #166. However, there are still two usages of yaml.js left in the codebase:

1. kaitai_struct_webide/src/KaitaiSandbox.ts

   Line 20 in 80c94b1

   "yamljs": "${npmDir}/yamljs/yaml",

   The actual usages to replace (the above line just sets up the yamljs package so that it can be imported) are in this file:

   kaitai_struct_webide/src/worker/KaitaiWorkerV2.ts

   Line 6 in 80c94b1

   import { YAML } from "yamljs";

2. kaitai_struct_webide/src/worker/ImportLoader.ts

   Line 8 in 80c94b1

   "yamljs": `${npmDir}/yamljs/yaml`,

Both of these places are not used from the v1 version that is currently active. They are associated with the v2 version (see #35). However, I can't get v2 working right now (it seems to be broken), so I did not replace the yaml.js usages there, because I wouldn't have had a way to test it.

On top of that, the src/worker/ImportLoader.ts file seems to be unused even from any v2 code present in the repository, so I guess it could be removed altogether? It appears to be some weird hackish way of handling imports, so we probably shouldn't be using it anyway.

After dealing with these usages, we'll be able to remove yaml.js from vendor.yaml:

kaitai_struct_webide/vendor.yaml

Lines 193 to 200 in 5de330d

	# FIXME: remove when no longer referenced by src/KaitaiSandbox.ts and src/worker/ImportLoader.ts
	# (see https://github.com/kaitai-io/kaitai_struct_webide/issues/168)
	yaml.js:
	source: https://github.com/jeremyfa/yaml.js
	licenseName: MIT
	licenseUrl: https://raw.githubusercontent.com/jeremyfa/yaml.js/develop/LICENSE
	npmDir: yamljs
	files: [LICENSE, dist/yaml.js]

This will cause yaml.js to no longer be available under the path lib/_npm/yamljs. Then the yamljs npm package won't actually be used anymore, so it should be removed from package.json as well:

kaitai_struct_webide/package.json

Line 28 in 80c94b1

"yamljs": "^0.3.0"