We were already using `gir -d` and especially now that our files are
separated across two directories that are relative to the directory
containing Gir.toml this only becomes cumbersome. Besides `gir` lacks
functionality to normalize the path, leading to ie.
gstreamer-gl/egl/sys/../../../gir-files in the version comment as a
result.
Otherwise the API of the base classes will be directly available and can
cause confusion (e.g. gst_base_src_set_format() vs. the "format"
property).
All base class API should be considered "protected" from an application
point of view and only be called by the subclass itself.
See https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/issues/872
