Bonfire of the gftools-scripts

gftools has become a bit of a dumping ground. I propose we deprecate/remove:

* compare_font (we have many compare_font utilities)
* fix_glyphs (it doesn't do much)
* font_diff (already deprecated, remove it next major version)
* font_weights_coverage (this should be a fontbakery check)
* sanity_check (we have fontbakery)
* space_check (already deprecated, remove it next major version)
* tag_noto (happens magically these days)
* test_gf_coverage (less useful now that the nam files cover half of unicode)
* update_families (probably left over from old fix scripts, expects all "old" files to be rename to "-old", which we don't do)

I propose we rename (on the basis that "check" should be for checking if something is OK, and "fix" should be fixing something, and neither should be about requesting information). (OTOH, many of these could be combined into a single utility for printing "stuff" from a TTF.) Following `list_italic_angle`, `list_panose` etc. we should have:

* check_bbox -> list_bbox
* fix_vendorid -> list_vendorid
* check_name -> list_name_table
* check_copyright_notice -> list_copyright_notice
* find_features -> list_layout_features
* fix_family_metadata -> list_family_metadata
* varfont_info -> list_fvar
* what_subsets -> list_subsets

Also: `push_stats` and `push_status` are one character different...

More contentious:

* add_axis - move to axisregistry?
* lang -> move to lang
* lang_sample_text -> move to lang
* namelist -> move to glyphsets
* rangify -> move to glyphsets or deprecate
* rename_font -> merge with update_nameids?
* unicode_names -> move to glyphsets or deprecate, now we have glyphsets/scripts/create-glyphset.py