UI: Make it more clear that public means read only and hide options if you don't have access

[kiddinn]

Is your feature request related to a problem? Please describe.
Public access to a sketch means read-only, yet that's not clear enough in the UI. Let's make that clear.

Secondly a user that has only read access to a sketch should perhaps not been shown all these things they don't have access to. So hiding things like adding a label and a comment to an event should be done.

We could even display somewhere the current premission you've got on a sketch to make it more clear.