Debugger: Add Disassembling of functions.

- Add "Disassemble function..." action with dialog for name
  to stack window.
- Add "Disassemble" with function name from code model to
  the Editor context menu.
- Change the engines to be able to disassemble a function without
  address.

Change-Id: I812f4672d97d9a866ee7f5a38dbd18b2876bccfa
Reviewed-by: hjk <qthjk@ovi.com>