(U+5BFB): Add `<-denotational@usage' for BUCS+5C0B; apply new

(U+5BFB): Add `<-denotational@usage' for BUCS+5C0B; apply new
conventions for glyph granularity.
(U+5C0B): Modify structure.
(CU+5C0B): Use `ideographic-structure@apparent' instead of
`ideographic-structure'.
(UU+5C0B): Modify structure; preserve the previous IDS as an apparent
structure.
(A-IWDSU+3777): New abstract node; use `<-denotational' for
A-cgnU+5C0B.
(U+3777): Add `<-denotational' for A-IWDSU+3777; apply new conventions
for glyph granularity.
(U-00021B36): Add `<-denotational' for A-IWDSU+3777; use
`ideographic-structure@apparent/rightmost' instead of
`ideographic-structure@apparent'.
(MJ057349): Use `ideographic-structure@apparent/rightmost' instead of
`ideographic-structure@apparent'.
(A2-DJT-02430): Unify BUCS+5C0B.