Move Manage Custom Parsers view menu item to tracing context menu

Move Manage Custom Parsers view menu item to tracing context menu

- The Manage Custom Parsers... command is removed from the Project
Explorer view menu, and added to the Traces folder context menu and to
the trace's Select Trace Type... context sub-menu.
- A bullet icon is added to the selected trace type's category menu item
in the Select Trace Type... context sub-menu.

Change-Id: I77156a8de320264c0fac3db623a2c9cf7831718e
Reviewed-on: https://git.eclipse.org/r/9233
Tested-by: Hudson CI
Reviewed-by: Bernd Hufmann <bhufmann@gmail.com>
IP-Clean: Bernd Hufmann <bhufmann@gmail.com>
Tested-by: Bernd Hufmann <bhufmann@gmail.com>
Reviewed-by: Patrick Tasse <patrick.tasse@gmail.com>