decoder_raw: Add option output_format

This option can use the following values:
- 'textual', to adjust output format to textual
- 'binary', to adjust format to binary
Default is textual as remains as such if nothing is specified.

Note that output format impacts only the get/peek SQL functions able to
query a replication slot.
decoder_raw: Fix regression tests

Regression tests have been broken by two things:
- Modification of option name from include-transaction to
include_transaction only applied on code and node regressions
- pg_create_logical_replication_slot returns slot_name and not anymore
slotname as column name.