Move mimetype definitions to plugin specs

- Avoids the hassle of QRC files and manually registering mime types
- Avoids performance regressions because of mime types that are
  registered after mime database has been used
- Makes it technically possible to detect that a disabled plugin could
  handle a mime type if it was enabled

Change-Id: I373008b1b56e9c6b4853055f20b3eeb112a6eff9
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
Reviewed-by: hjk <hjk@qt.io>

src/plugins/perforce/perforceplugin.cpp

@@ -45,7 +45,6 @@
 #include <coreplugin/locator/commandlocator.h>
 #include <texteditor/textdocument.h>
 #include <utils/fileutils.h>
-#include <utils/mimetypes/mimedatabase.h>
 #include <utils/parameteraction.h>
 #include <utils/qtcassert.h>
 #include <utils/synchronousprocess.h>
@@ -186,8 +185,6 @@ bool PerforcePlugin::initialize(const QStringList & /* arguments */, QString *er
 
     initializeVcs(new PerforceVersionControl(this), context);
 
-    Utils::MimeDatabase::addMimeTypes(QLatin1String(":/trolltech.perforce/Perforce.mimetypes.xml"));
-
     m_instance = this;
 
     m_settings.fromSettings(ICore::settings());