FakeVim: implement C-u in insert mode
FakeVim: implement C-u in insert mode

In insert mode:
input:  "aaa bbb ccc|"
keys:   C-u
result: ""

Change-Id: I1813369c401aaee1a634c363ca5f4c252062613c
Reviewed-by: hjk <4622a3e4640ee19ab4ebad197849e45b7170d50c@theqtcompany.com>

Distrotech/qtcreator,xianian/qt-creator,Distrotech/qtcreator,martyone/sailfish-qtcreator,danimo/qt-creator,xianian/qt-creator,Distrotech/qtcreator,danimo/qt-creator,Distrotech/qtcreator,Distrotech/qtcreator,xianian/qt-creator,martyone/sailfish-qtcreator,danimo/qt-creator,martyone/sailfish-qtcreator,danimo/qt-creator,danimo/qt-creator,xianian/qt-creator,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,Distrotech/qtcreator,danimo/qt-creator,danimo/qt-creator,Distrotech/qtcreator,xianian/qt-creator,xianian/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator,xianian/qt-creator,xianian/qt-creator,martyone/sailfish-qtcreator,danimo/qt-creator,danimo/qt-creator,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator