[vscode] Revisit how we manage our YAML fields and descriptions

[spalmurray-codecov]

In all likelyhood, the LSP hints for our yaml fields are out of date in places. Go through the values and descriptions and cross check with documentation, updating where necessary.

[spalmurray-codecov]

Spent a day getting confused by this trying to update the schema with latest from API. I think there's more work we can do here to make this process better. It feels like a waste of time to manually update the API schema to get along with the vscode extension schema, so I'm not going to do that now.

Path forward:

Let's settle on one method for adding descriptions to YAML fields. I say let's do this on API side so it will be done when folks are adding new fields. Then the extension side is really easy, just update the schema with the latest API version and convert to the correct format.

Achieving this will take some effort to

1. decide on a format for adding descriptions in API,
2. move the old descriptions over to API (removing from here),
3. adapt the conversion script to work with the format we settle on for descriptions, and
4. fill in any missing descriptions.

After all of this is done, we will be in a much better place for keeping everything up-to-date.

That said, there has also been talk of deprecating the YAML, so if that's going to be the case there's probably no point in doing any of this.