[cff] late size checks

Hi Werner,

I noticed late size checks in the cff driver, in cff_glyph load and
cff_slot_load. There is nothing like that in the TrueType driver.
There is also https://gitlab.freedesktop.org/freetype/freetype/-/commit/e02a40a4f8754774c8dccc01aeb0f07ea58e81c7,
which curiously fixes cff_get_advances actually. I also see that
FT_Load_Glyph pre-checks face->size while FT_Get_Advances does not.
Hence, I have the following  questions.

Should we check face->size in FT_Get_Advances as well? Then we can get
rid of all late size checks in CFF.

It seems that arbitrary face-size is required even with
FT_LOAD_NO_SCALE. The docs talk about something else instead.

Thanks,
Alexei