To reproduce:
In the Android settings, enabled "Automatically create kits"
  -> This creates kits with autodetected set to true
Switch to the kits page to get the KitPage filled, those kits
  now appear under the autodetected node.
Switch to the Android settings and disable "Automatically create kits",
  -> This doesn't want to delete the old kits, to not throw away user
     settings, so the kits are marked as manual by calling setAutoDetected
Switch to the Kit page and notice the kits still listed under the
  autodetected node. Clicking apply enables the remove button and on
  removing Creator crashes.

Add the necessary signal emissions to setAutoDetected and several other
methods and fix the KitModel to cope with changes to autodetected.

Task-number: QTCREATORBUG-13736
Change-Id: I3d0ff247a6bfff8ace53df8535749db5c736d54b
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>