pgsql: Display the names of missing columns in error during logical rep

Display the names of missing columns in error during logical replication.

In logical replication when a subscriber is missing some columns, it
currently emits an error message that says "some" columns are missing, but
it doesn't specify the missing column names. Change that to display
missing column names which makes an error to be more informative to the
user.

We have decided not to backpatch this commit as this is a minor usability
improvement and no user has reported this.

Reported-by: Bharath Rupireddy
Author: Bharath Rupireddy
Reviewed-by: Kyotaro Horiguchi and Amit Kapila
Discussion: https://postgr.es/m/CALj2ACVkW-EXH_4pmBK8tNeHRz5ksUC4WddGactuCjPiBch-cg@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/f07707099c17e7ff66eac7d38cbd1148672f7ee4

Modified Files
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src/backend/replication/logical/relation.c | 55 ++++++++++++++++++++++++------
1 file changed, 45 insertions(+), 10 deletions(-)