Add support for Grafana Library Panels

[malcolmholmes]

Adds support for Grafana library panels to Grizzly.

Also starts a transition to using the Golang client for Grafana. When
Grizzly was started, this was not sufficiently mature. This is no longer
the case. A transition to the golang client should reduce the amount
of code required in Grizzly.

[CLAassistant]

All committers have signed the CLA.

[hsyed-dojo]

LGTM

[hsyed-dojo]

nit: a type assertion here would be nice to assert that LibraryPanelHandler conforms to grizzly.Handler.

[ccjones88]

So I pulled this down locally to try it out and I'm kind of caught in this catch 22 of both dashboards using the library panel and the library panel itself saying that it cannot be found.

Steps for reproducing:

1. Have two dashboards sharing 1 or more library panels
2. grr pull library panels/dashboards ( I myself am using grr pull -d resources -t "LibraryPanel/*" -t "Dashboard/*" -l debug )
3. Next grr apply to a Grafana instance that does not have those dashboards/library panels already existing. I've tried quite a few different ways here:

• grr apply -d resources -t "Dashboard/*" -t "LibraryPanel/*" -l debug
• grr apply -d resources -t "LibraryPanel/*" -t "Dashboard/*" -l debug
• grr apply -d resources -t "LibraryPanel/SpecificUID" -l debug
• grr apply -d resources -t "Dashboard/SpecificUID" -l debug
• grr apply -d resources -t "LibraryPanel/SpecificUID" -t "Dashboard/SpecificUID" -l debug

Dashboard apply always ends up with {"message":"Error while connecting library panels"}
LibraryPanel apply has {"message":"library element could not be found"}
Server Side logs show level=error msg="Error while connecting library panels" error="library element could not be found" corresponding to grr apply for the Dashboard and level=error msg="library element could not be found" error="library element could not be found" corresponding to grr apply for Library Panels

My guess would be that, when trying to grr apply -d resources -t "LibraryPanel/*" it goes to get the remote value and then doesn't handle the value not existing and just has a fatal err. When ideally, it would handle it like dashboards and say LibrayPanel.UniqueID was not found, adding it...

I'm hoping I'm just missing something obvious, but figured it'd be beneficial to let you all know now before it's merged in case there is a further bug here. Let me know if I can add any more info.

Grafana v9.1.5
grr version dev-v0.2.0-1-g5f400a8-dirty

[theSuess]

Resolved in #282