[Feature] Create handlers for checking if session is valid

[YourTechBud]

Need to make two handlers in the auth provider and admin manager respectively

• deny-user
  • This plugin immediately sends a 403.
  • Implement this in the auth provider.
  • We need to make sure that one entry for this plugin (name will be empty string) is added in the plugin list that we return in #1689.
• authenticate-user
  • This will merely check if the user session is valid by checking the types.AuthResult object present in the context
    • Return 401 if user is not authenticated
    • For authResult reference use: https://github.com/spacecloud-io/space-cloud/blob/sc-poc/sc-poc/modules/auth/handler_auth_opa.go#L46
  • We need to make sure that one entry for this plugin (name will be empty string) is added in the plugin list that we return in #1689.
• authenticate-sc-user
  • This checks if user is authenticated for by using the admin secret. Send 403 if token is not present or if token is invalid.
  • Consider making this handler in the admin module
  • This handler will have to perform a jwt validation using the admin secret provided in #1686
  • This plugin will not be returned in the plugin details list.

Also, make sure the following sc apis use the authenticate-sc-user plugin:

• All CRUD APIs
• the get crds api
• The pubsub consumer channels for asyncapi and openapi. The producer channels will have the deny-user plugin
• The get plugin details api

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