Get rid of QtcProcess::workingDirectory() overload

Adapt all callers' code so that it passes the FilePath
instead of QString. As a consequence introduce
TemporaryDirectory::masterDirectoryFilePath() and use
it where easily possible.

Change-Id: I14564949b3b916921e32a2957c84c03d1da43af2
Reviewed-by: hjk <hjk@qt.io>

src/plugins/docker/dockerdevice.cpp

@@ -1721,7 +1721,7 @@ bool DockerDevicePrivate::runInContainer(const CommandLine &cmd) const
 
     QtcProcess proc;
     proc.setCommand(dcmd);
-    proc.setWorkingDirectory(QDir::tempPath());
+    proc.setWorkingDirectory(FilePath::fromString(QDir::tempPath()));
     proc.start();
     proc.waitForFinished();