Fix avdmanageroutputparser test

- There is no PLUGIN_DEPENDS for tests, and it wouldn't work anyhow
  because of duplicated symbols. It was interpreted as a dependency and
  the test disabled because no such target exists.
- Move the platformNameToApiLevel(...) function to
  avdmanageroutputparser.h to break the dependency to a lot of Android
  support code.

Amends 78da7e2922

Change-Id: I6933684a76e5291d415c72388caa3df2bee7cbfb
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/android/avdmanageroutputparser.h

@@ -31,6 +31,7 @@ namespace Internal {
 const char avdManufacturerError[] = "no longer exists as a device";
 
 AndroidDeviceInfoList parseAvdList(const QString &output, QStringList *avdErrorPaths);
+int platformNameToApiLevel(const QString &platformName);
 
 } // namespace Internal
 } // namespace Android