Add new ReadConfigAction auth action for reading config

[daniel-shuy]

This PR creates ReadConfigAction, a new auth action for reading config, instead of ListRepositoriesAction.

Closes #764

[ozkatz]

Thanks for this - PR looks great!
Just a couple of small things that I think are missing:

1. documentation under docs/reference/authorization.md (there's a table listing all available permission actions that needs to be updated)
2. under auth/setup.go - the built-in "Admins" group should probably come with the appropriate policy that allows to perform this action

[daniel-shuy]

documentation under docs/reference/authorization.md (there's a table listing all available permission actions that needs to be updated)

Done!

under auth/setup.go - the built-in "Admins" group should probably come with the appropriate policy that allows to perform this action

AuthFullAccess already imports all auth actions (auth:*)

[ozkatz]

Looks great! Thanks for the contribution 🥳