[AltspaceVR] Improve config UI in SDKApp Space Component

[eanders-ms]

The SDKApp Space Component UI should be able to accept a multi-line text blob that would be passed to the app when the connection is made. If the connection results in a new session getting spawned, this text blob would be passed to it in onStarted. This would enable the creation of reusable, customizable, generic apps anyone can use. Examples:

• Make an MRE app that is a generic video player anyone can use. The playlist is configured on the app spawner.
• Make a generic dressing room app. The specific clothing items and configuration for each such as attach point, scale, rotation and offset are configured in a JSON blob on the app spawner.

This kind of thing is technically possible now using query params, but it is very cumbersome.

[willneedit]

This could even be extended.

On entering the URL in the config UI, the client contacts the MRE in a special "query mode", perhaps with a dedicated file part of the URL, and retrieves a description of the parameter list, maybe

[
 [ "name", "string" ],
 [ "value", "number" ],
]

which allows the UI to reconfigure itself to include the additional data fields.