RBAC permissions to allow user to only list actions for certain packs

[amanda11]

This issue arose from the discussions in StackStorm/st2docs#1107 in regard to the behaviour in the example in the documentation.

In the current example the user had permissions

permission_grants:
    -
        resource_uid: "pack:example"
        permission_types:
           - "pack_all"
           - "sensor_type_all"
           - "rule_all"
           - "action_all"

With this permission the user was unable to run "st2 action list" or "st2 action list -p example".

The only way the user could list the actions in the pack was to add the global action_list permission, and then they were able to list the actions in that and all other packs.

See the comments in the existing issue from @satellite-no StackStorm/st2docs#1107 (comment), and @amanda11 StackStorm/st2docs#1107 (comment) about two different possibilities of how the permissions could be viewed/altered to support restricting the list to certain packs.