cqlsh: Add extension handler for "scylla_encryption_options"

[fruch]

Refs scylladb/scylla-tools-java#731

Scylla encryption options are not stored with "normal" options. Because these are 100% intertwined with drivers, and adding stuff there breaks things.

Instead they are extensions. The python driver allows adding extension handlers to print info about these.

This adds a handler, and while the end result will not be the actual cql statement to recreate the table, it at least will provide feedback to the user.

v2:

• format comments
• indentation

[fruch]

Some enterprise dtest started failing cause the encryption options are missing, seem like I've missed one commit during the transfer from scylladb/scylla-java-tools