shared: common: Add mountPaths()

Mountpaths indicate mount points of external devices. Files
located under such paths should not be removed on sync, because
they may have not been deleted, but are just inaccessible right now.

shared/common.h

@@ -12,7 +12,9 @@ QString findInPath(QString needle);
 bool initSqliteDatabase(QString path);
 void ensureConfigured();
 QStringList excludedPaths();
+QStringList mountPaths();
 bool isTextFile(QFileInfo fileInfo);
+bool isMountPath(QString path);
 QString versionText();
 } // namespace Common
 #endif