[IDEA] Add Backend Support for a Web Administrator

[gibson9583]

A web version of the client administrator is a nice feature to have, but there are additional endpoints required in the engine to properly support a web client.

[NicoPiel]

Like what?

[gibson9583]

Like what?

@NicoPiel :

1. Message tree serialization — the transformer/filter message trees need serialization for each data type. The Swing client gets this by calling the datatype serializers in-process; a browser can't.
2. Script tooling — the script editors validate and format JavaScript
3. Web-plugin delivery — An extension can ship a browser UI in a folder within the zip. The Swing client loads ClientPlugin classes from the jars, but a web client needs the engine to serve that UI over REST, so a plugin's UI follows the engine it's installed on rather than installing on the web admin's filesystem.