Add plugin support on the frontend

[ajatprabha]

Ref: #4069

• List registered plugins in a ResourceList based component
• Add a link to all plugins in the Sidebar
• Add a route for plugin UI to render
• Render the AOT compiled plugin at runtime.
• Error Handling
• Fetch plugins based on the namespace

[ajatprabha]

Current progress:

1. List of installed plugins

2. A sample plugin displaying available pods in the cluster

[maciaszczykm]

Testing it :)

[maciaszczykm]

The plugin works, that's great.

Few remarks from my side:

• If there is no Plugin CRD registered in the cluster I'd avoid listing Plugins in the menu. Thanks to that users can use dashboard like they do now if the have no plugins. Otherwise, when they enter plugin page they will see errors:

Another thing to consider here might be adding CRD from our backend and listing Plugins in the menu only if there are any plugins in the cluster.

• I'd like to know more how the plugins can be created. Which parts of the backend I can use, which parts of the frontend I can use. How to build the plugins. It will require some detailed documentation.

• Can you add plugin that uses material design card and styling is similar to the rest of the app? It would be valuable to show it to the people.

• I'd really appreciate possibility to pin some of the plugins to the menu like we advised for CRDs. I mean in this demo plugin1 could be pinned to the menu and then appear just under Plugins. Like Pods appear under Workloads.

At the moment that's it. I really appreciate all the effort and I think most crucial part is already done. Keep it up!

[floreks]

I have found a couple of issues while testing:

• Not working with secure Dashboard (login enabled)
  
• Delete and edit is available on the plugin list but it is not working
  
• Sorting not applied on the plugin list when first entering the page, only after manually hitting sort or clicking again on Plugins entry.

Questions:

1. How dependencies are calculated?
2. Are we able to inject plugin view into any view?

Besides that, really nice progress. It looks better and better.

[codecov]

Codecov Report

Merging #4094 into master will increase coverage by 0.56%.
The diff coverage is 45.76%.

@@            Coverage Diff             @@
##           master    #4094      +/-   ##
==========================================
+ Coverage   46.01%   46.57%   +0.56%     
==========================================
  Files         198      200       +2     
  Lines        9300     9366      +66     
  Branches      105      105              
==========================================
+ Hits         4279     4362      +83     
+ Misses       4760     4735      -25     
- Partials      261      269       +8

Impacted Files	Coverage Δ
src/app/backend/api/types.go	38.88% <ø> (ø)	⬆️
src/app/backend/handler/apihandler.go	27.81% <0%> (+0.57%)	⬆️
...rontend/common/components/resourcelist/groupids.ts	100% <100%> (ø)	⬆️
src/app/backend/plugin/handler.go	78.94% <100%> (+53.3%)	⬆️
.../app/frontend/common/services/resource/endpoint.ts	79.24% <100%> (+0.39%)	⬆️
src/app/frontend/login/component.ts	79.16% <100%> (+0.9%)	⬆️
src/app/backend/plugin/config.go	48.64% <48.64%> (ø)
src/app/frontend/common/services/global/plugin.ts	50% <50%> (ø)
src/app/backend/client/verber.go	66.26% <50%> (-1.64%)	⬇️
src/app/backend/client/manager.go	64.37% <71.42%> (+1.82%)	⬆️
... and 5 more

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[floreks]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ajatprabha, floreks

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