gstreamer1.0-python: rework gobject-introspection handling

gstreamer1.0-python: rework gobject-introspection handling

gobject-introspection is mandatory for gstreamer1.0-python - there is no
configure option to enable or disable it.

To handle properly, this patch does:

* Make 'gobject-introspection-data' a required distro feature
* Add
  'UNKNOWN_CONFIGURE_WHITELIST_append = " --enable-introspection --disable-introspection"'
   - it was removed in gobject-introspection.bbclass to avoid
  | ERROR: libgee-0.18.0-r0 do_configure: QA Issue: libgee: configure was passed unrecognised options: --disable-schemas-install [unknown-configure-option]

Signed-off-by: Andreas Müller <schnitzeltony@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>