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/git/gitplugin.cpp

@@ -59,7 +59,6 @@
 
 #include <coreplugin/messagebox.h>
 #include <utils/asconst.h>
-#include <utils/mimetypes/mimedatabase.h>
 #include <utils/qtcassert.h>
 #include <utils/parameteraction.h>
 #include <utils/pathchooser.h>
@@ -99,7 +98,6 @@ namespace Git {
 namespace Internal {
 
 const unsigned minimumRequiredVersion = 0x010800;
-const char RC_GIT_MIME_XML[] = ":/git/Git.mimetypes.xml";
 
 const VcsBaseEditorParameters editorParameters[] = {
 {
@@ -642,8 +640,6 @@ bool GitPlugin::initialize(const QStringList &arguments, QString *errorMessage)
     connect(VcsManager::instance(), &VcsManager::repositoryChanged,
             this, &GitPlugin::updateBranches, Qt::QueuedConnection);
 
-    Utils::MimeDatabase::addMimeTypes(RC_GIT_MIME_XML);
-
     /* "Gerrit" */
     m_gerritPlugin = new Gerrit::Internal::GerritPlugin(this);
     const bool ok = m_gerritPlugin->initialize(remoteRepositoryMenu);