Plugin Tests: Create settings dir with QTemporaryDir
Plugin Tests: Create settings dir with QTemporaryDir

Create a clean and unique settings directory for "-test" runs if no
settings path is provided explicitly.

Change-Id: Ida2f5a74d42a5292963dd8d5d1f9dcddcdd24fd4
Reviewed-by: Christian Stenger <accbb51712d7b9c4fb108439d01e716148e5f9e6@theqtcompany.com>

danimo/qt-creator,amyvmiwei/qt-creator,xianian/qt-creator,AltarBeastiful/qt-creator,xianian/qt-creator,amyvmiwei/qt-creator,kuba1/qtcreator,xianian/qt-creator,martyone/sailfish-qtcreator,AltarBeastiful/qt-creator,farseerri/git_code,kuba1/qtcreator,danimo/qt-creator,AltarBeastiful/qt-creator,danimo/qt-creator,amyvmiwei/qt-creator,farseerri/git_code,Distrotech/qtcreator,Distrotech/qtcreator,martyone/sailfish-qtcreator,danimo/qt-creator,AltarBeastiful/qt-creator,kuba1/qtcreator,AltarBeastiful/qt-creator,xianian/qt-creator,AltarBeastiful/qt-creator,farseerri/git_code,martyone/sailfish-qtcreator,amyvmiwei/qt-creator,xianian/qt-creator,kuba1/qtcreator,Distrotech/qtcreator,kuba1/qtcreator,amyvmiwei/qt-creator,xianian/qt-creator,amyvmiwei/qt-creator,Distrotech/qtcreator,xianian/qt-creator,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,danimo/qt-creator,Distrotech/qtcreator,xianian/qt-creator,danimo/qt-creator,kuba1/qtcreator,xianian/qt-creator,farseerri/git_code,danimo/qt-creator,martyone/sailfish-qtcreator,danimo/qt-creator,amyvmiwei/qt-creator,kuba1/qtcreator,Distrotech/qtcreator,kuba1/qtcreator,AltarBeastiful/qt-creator,farseerri/git_code,martyone/sailfish-qtcreator,farseerri/git_code,farseerri/git_code,AltarBeastiful/qt-creator,Distrotech/qtcreator,danimo/qt-creator,amyvmiwei/qt-creator,martyone/sailfish-qtcreator,kuba1/qtcreator,martyone/sailfish-qtcreator,farseerri/git_code