Utils/Ssh: Move SshRemoteProces::isRunning() to QtcProcess base

... and use it on a few places.

Change-Id: Id2cea709e355a46821a720e593740ac032888ced
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/libs/utils/qtcprocess.h

@@ -171,6 +171,7 @@ public:
 
     QProcess::ProcessError error() const;
     QProcess::ProcessState state() const;
+    bool isRunning() const; // Short for state() == QProcess::Running.
 
     QString errorString() const;
     void setErrorString(const QString &str);