(A-BC-8875): Add `<-denotational@component' for A-IWDSU+21D05.

(A-BC-8875): Add `<-denotational@component' for A-IWDSU+21D05.
(BC-8875): Add U+5DFF as a target of `<-unknown'.
(U-00021D05): Add `<-denotational@component' for A-IWDSU+21D05; apply
new conventions for glyph granularity for components of
ideographic-structure.
(GT-K01900): Use `<-denotational' instead of
`<-denotational@component' for A-BC-8875; use
`<-denotational@component' instead of `<-denotational' for U-00021D05;
unify CB07138.
(A-IWDSU+21D05): New abstract node.