Don't show clusters and templates permission errors if viewing apps/sources

[foot]

• Refactors Clusters and Templates contexts into hooks
  • As the selectedClusters state (which clusters to delete) is no longer in a common context between the deleteClusterDialog and the clustersList we do a small refactor and clear the selectedClusters onDialogClose instead of having the Dialog do that itself.

Fixes #1422

To test:

Pre-reqs:

• Be part of the wge group: https://gitlab.git.dev.weave.works/wge/

Test

• Login to https://35.188.40.143:30080/ with OIDC + gitlab, navigate to apps/sources, wait ~20s, see the error toast about no gitopscluster/capitemplates permissions.
• Checkout this branch locally and run: PROXY_HOST=https://35.188.40.143:30080/ yarn start
• Login with OIDC + gitlab, The redirect will be incorrect and needs correction, when you see an error in the browser, edit the URL manually, replacing https://35.188.40.143:30080/ with http://localhost:3000 and hit enter and you should be logged in locally.
• Notice no more errors on the apps/sources page.

[ahussein3]

LGTM. Well done now we have reduced the API calls by 2
💯

[ahussein3]

@foot the only tiny thing I would suggest is to find better name for onRequestClose,handleRequestClose for maybe something like ResetDialogOnClose. as RequestClose is like confusing as there is no actual request. just my opinion.

[foot]

Great point, I was trying to be consistent w/ mui but got that wrong 😅 . They just call it onClose https://v4.mui.com/api/dialog/ will do that.