Merged pull request https://github.com/scylladb/scylla/pull/5910 by
Calle Wilund:
Rename metadata and data columns according to new spec
Also use transformation methods for names in all code + tests
to make switching again easier
Break up data column tuple
Data column is now pure frozen original type.
If column is deleted (set to null), a metadata column cdc$deleted_ is set to true, to distinguish null column == not involved in row operation
For non-atomic collections, a cdc$deleted_elements_ column is added, and when removing elements from collection this is where they are shown.
For non-atomic assign, the "cdc$deleted_" is true, and is set to new value.
column_op removed.
359b32fb63