Use a static page title for about:torconnect

Currently the about:torconnect page title (tab name) changes whenever the page's heading changes.

I think we should just have a static title:

• A changing title is visually distracting.
• A changing title may be communicated to screen readers, which would be duplicate information since the heading changes would be known.
• Any information about the status of the connection is already indicated in the application windows toolbar in the Tor connection status area.
• It makes the maintenance of the code simpler.

@donuts @felicia some choices for the title (tab name):

1. "Connect to Tor". This matches the current initial title.
2. "Connect". Shorter.
3. "Connect to the Tor network". Clearer, but much more verbose.
4. "Tor connection". Matches the tooltip for the toolbar area.
5. Something else?