Fix component add/change and delete dialogs

A few things here:
  - 'New conversation' and 'New channel' feel better off in the template than inside an html element attribute with js inside of it. Any way for us to get it to work that way instead?
  - I'm guessing the `'bulk-message'` part is temporary, but I'd rather avoid this. We don't know up front what type of conversation or channel to create, that needs to be figured out as the next step when creating the component. It would be better if we could get the code to work that way, where we specify the type of conversation or channel in the form. Type-specific handling is out of this scope, we can think of how to handle that later.
  - Do we maybe want separate methods for opening an existing component form, creating a new component form, and one for opening *and* creating (that just delegates to the two previous ones)? The create one and the create-and-open one should ideally only need the component type as an argument.

Thoughts?