(chise-json-char-get-normalized-spec): Support `=decomposition@cid',
`=decomposition@hanyo-denshi' and `=decomposition@mj'.
(chise-json-separate-normalized-spec): Support `=decomposition';
change the format of return value.
(chise-json-char-get-info): Support `=decomposition'; modify for
`chise-json-separate-normalized-spec'; use "subsumed-in" instead of
"<-subsumptive@nil" for `<-subsumptive'.