Add support for binary I/O of ltree, lquery, and ltxtquery types.
Not much to say here --- does what it says on the tin. The "binary"
representation in each case is really just the same as the text format,
though we prefix a version-number byte in case anyone ever feels
motivated to change that. Thus, there's not any expectation of improved
speed or reduced space; the point here is just to allow clients to use
binary format for all columns of a query result or COPY data.
This makes use of the recently added ALTER TYPE support to add binary
I/O functions to an existing data type. As in commit
a80818605,
we can piggy-back on there already being a new-for-v13 version of the
ltree extension, so we don't need a new update script file.
Nino Floris, reviewed by Alexander Korotkov and myself
Discussion: https://postgr.es/m/CANmj9Vxx50jOo1L7iSRxd142NyTz6Bdcgg7u9P3Z8o0=HGkYyQ@mail.gmail.com