Locator: Shuffle the priorities a bit

Introduce a "Highest" priority for the filters-filter. Keep "Low"
available for lower priority than the default all projects and current
project filter.

Change-Id: I9152d2e6c64b65478416cee18183bce1240ee187
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>

src/plugins/cmakeprojectmanager/cmakelocatorfilter.cpp

@@ -50,6 +50,7 @@ CMakeLocatorFilter::CMakeLocatorFilter()
     setId("Build CMake target");
     setDisplayName(tr("Build CMake target"));
     setShortcutString(QLatin1String("cm"));
+    setPriority(High);
 
     connect(SessionManager::instance(), SIGNAL(projectAdded(ProjectExplorer::Project*)),
             this, SLOT(slotProjectListUpdated()));