tags: update to latest iso-code and support more languages

tags: update to latest iso-code and support more languages

Some languages have an ISO 639-2 representation but no 639-1
representation, for example where "eng" has a two-letter
equivalent in "en", "enm" doesn't have one.

Discarding those languages from our static table caused functions
such as gst_tag_get_language_code_iso_639_2T() or
gst_tag_get_language_code_iso_639_2B() to return NULL for
valid language codes such as "enm", potentially causing users
of these API such as mpegtsmux to discard language code tags
as invalid.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/785>