Allow VSCode-Specific Extensions in Schemas about minecraft-bedrock-json-schemas

Oh, I apologize. I had forgotten to update this with demonstrations.

Here's an example that demonstrates an author going through a full a feature rule:

In the most radical case, the vanilla definitions can be included for quick searching and overriding:

Error messages are great. Normally, when a property accepts multiple types, the default error reports that the property must be exactly one of those types, not mentioning the others. No longer:

User authoring flow has been improved. Properties that are irrelevant under the current circumstances are not shown. And if they would error, the user can be given specific feedback:

Another cool feature that's hard to highlight is that a namespace is automatically coerced from the VSCode Workspace name, if one exists. It's transformed to [a-z0-9_] if possible. Additionally, the feature rule identifier is set to the filename automatically. Also, Markdown descriptions would make in-place linking to the Microsoft Creator docs a breeze… if such docs existed for feature rule.

These all use VSCode's native extensions to the JSON schema. I'm not sure how "standard" you would consider these, which is why I filed this issue. In any case, I'd like to know before continuing to the feature types if these extensions are desired/allowed in this repository. While I think the improvements using these extensions are substantial and I'll personally be using them, authoring these extensions definitely takes more time.

[DaanV2]

This look good, yeah why not

Alright, thank you. I'll see what I can do.