Remove dependency on real ActionManager from test.

ActionComponentChain can be passed a simple mocked ActionManager,
instead of using a real ActionManager which requires half the
client to be initialised (via TestMain).

Change-Id: I294285d170e8facfa00e49683dd61068725d4f3e
Reviewed-on: http://gerrit.dmdirc.com/2657
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Automatic-Compile: DMDirc Build Manager