This moves one check for conflicting options from the archive restore
code to the main function where other similar checks are performed.
Also reword the error message to be consistent with other messages.

The only option combination impacted is --create specified with
--single-transaction, and informing the caller at an early step saves
from opening the archive worked on.  A TAP test is added for this
combination.

Author: Daniel Gustafsson
Reviewed-by: Fabien Coelho
Discussion: https://postgr.es/m/616808BD-4B59-4E6C-97A9-7317F62D5570@yesql.se