Figure out testing regime for sandbox code and dropserver_app lib

[teleclimber]

We need to develop an automated testing suite that can match up:

• dropserver_app (published library)
• deno sandbox code (ships with ds-host and ds-dev)
• deno version

Note these:

• dropserver_app
  • sets dropserver_lib_support interface version
  • sets nominal deno std lib version
• deno sandbox code
  • expects a range of dropserver_lib_support interface, or something like that?
  • also sets its own std lib version
• deno version
  • May or may not work with certain std lib versions.
  • Varies the Typescript version in use

Ultimately we are testing to ensure an app works, so the test should load a set of tests that can be performed against dropserver_app lib, while varying dropserver versions and deno versions.

Quite unsure what this actually looks like though.

[teleclimber]

Finding that current integrated testing stuff is pretty hard to maintain. Whatever this testing regime is, should probably serve as all-up integration test too while we're at it.

[teleclimber]

I have started developing a way to test compatibility between different versions of dropserver_lib_support, at least at the Typescript types level. This helps ensure some level of compatibility but there are many ways that this would be insufficient to guarantee compatibility.