(U+5DE9): Add `<-denotational@usage' for BUCS+978F and A2-DJT-02777;

(U+5DE9): Add `<-denotational@usage' for BUCS+978F and A2-DJT-02777;
add `sound@ja/on'.
(A-compU+5DE9): New abstract node; use `<-denotational' for U+5DE9.
(o-JU+5DE9): Use A-compU+5DE9 instead of U+5DE9 as its mother; apply
new conventions for glyph granularity.
(A-UU+5DE9): Likewise.
(A-U+5DE9-var-001): New abstract node; use `<-denotational' for
U+5DE9.
(U+5DE9-var-001): Use A-U+5DE9-var-001 instead of U+5DE9 as its
mother.
(U-0002201C): Add `<-denotational@usage' for A2-DJT-02777; apply new
conventions for glyph granularity.
(A2-DJT-02777): New abstract node.