Utils: Add CommandLine convenience constructors

... taking a QString for the executable.

This weakens the very explicit QString -> FileName conversion via the
named constructors for the special case of constructing a CommandLine.

I think that's worthwhile here, as it reduces the noise on the caller
site under circumstance where the nature of the thing is obvious.

Change-Id: I27b4a73639728893d053b2e7ba65cb745f0ffe83
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/libs/utils/fileutils.cpp

@@ -74,10 +74,18 @@ namespace Utils {
 
 */
 
+CommandLine::CommandLine(const QString &executable)
+    : m_executable(FilePath::fromString(executable))
+{}
+
 CommandLine::CommandLine(const FilePath &executable)
     : m_executable(executable)
 {}
 
+CommandLine::CommandLine(const QString &exe, const QStringList &args)
+    : CommandLine(FilePath::fromString(exe), args)
+{}
+
 CommandLine::CommandLine(const FilePath &exe, const QStringList &args, MetaCharMode metaCharMode)
     : m_executable(exe)
     , m_metaCharMode(metaCharMode)