Allow logical replication to copy tables in binary format

Hey hackers,

I see that logical replication subscriptions have an option to enable
binary [1].
When it's enabled, subscription requests publisher to send data in binary
format.
But this is only the case for apply phase. In tablesync, tables are still
copied as text.

To copy tables, COPY command is used and that command supports copying in
binary. So it seemed to me possible to copy in binary for tablesync too.
I'm not sure if there is a reason to always copy tables in text format. But
I couldn't see why not to do it in binary if it's enabled.

You can find the small patch that only enables binary copy attached.

What do you think about this change? Does it make sense? Am I missing
something?

[1] https://www.postgresql.org/docs/15/sql-createsubscription.html

Best,
Melih