Support requesting a whole dict at a time

[ec429]

When requesting an array, such as "?a=r.resource", without specifying a key, it would be nice if the value was returned as a dict of all resources on board. JSON should be able to handle this fine.
Similarly, "?a=b.name" should return a list of the names of all bodies, in order of their body id.
Currently, one instead gets a 500 with an index out of range exception, for both of these requests.

This would help interoperability with mods like RealFuels that greatly proliferate the number of different resources.

[larkin]

Similar point here, it would be great to have a way to list all of the available telemetry points on a vehicle so that we could easily allow exploration in a front end interface. We have a lot of people interested in using Telemachus to integrate with Open MCT and this would be a great way to keep in sync.

See related comments in nasa/openmct#1064

[richardbunt]

The a.api API string will dump all available endpoints.

[hudsonfoo]

For any Telemachus users who are interested in integrating with OpenMCT: nasa/openmct#1146