macdeployqt doesn't deploy plugins when build qt with custom -plugindir and frameworks in app bundle cannot resolve rpath

If configure qt use -plugindir with path other than plugins, macdeployqt doesn't copy the plugins into the app bundle, the PlugIns directory doesn't exist.

Related github issue can be found in https://github.com/Homebrew/homebrew-core/issues/73019

After deploying app, some plugin cannot resolve the rpath, log: https://github.com/Homebrew/homebrew-core/files/6152905/macdeployqt.log