Feature/extra summary

[i-hate-nicknames]

Did you run make format && make check?
Yes

Fixes #646

Changes:

• Add GET /api//visors-summary endpoint, allowing to fetch detailed information about each visor

How to test this PR:
Run a hypervisor with some visors and query GET /api//visors-summary.

[jdknives]

Is there currently any possiblity of this code executing when hv.Visor would be nil?

[i-hate-nicknames]

Indeed there isn't. I took the code for getting visors and modified it to have additional info in response. However, we never start hypervisor without visor, except in tests. However, some tests rely on nil response on an "empty" hypervisor. Not sure if it's worth the trouble to change the tests and remove nil-checks everywhere.

[Senyoret1]

This is working well. I would just remove the dmsg field, because it appears to always return null and the data needed is in the dmsg_stats field, and the routes field, because it is not needed for the visor list and I think it could sometimes contain a lot of data, which would just unnecessarily degrade the performance. However, if there are reasons for keeping them there, then there is no problem

[i-hate-nicknames]

@Senyoret1 no other reasons besides just composing existing structures instead of declaring new ones. If you don't need that info it's no problem to avoid sending it.

[Senyoret1]

I checked and #699 contines working after the changes.