cqlshlib: added schema extensions for cdc and scylla_tags
cqlshlib: added schema extensions for cdc and scylla_tags

`DESC TABLE tbl` called on table with cdc (or on alternator table)
now prints, respectively, cdc options or `scylla_tags`.

This change accompanies PR scylladb/scylla#5720
Refs scylladb/scylla#5589
scylladb/scylla-tools-java,scylladb/scylla-tools-java,scylladb/scylla-tools-java,scylladb/scylla-tools-java