Test replay of regression tests.

Test replay of regression tests.

Add a new TAP test under src/test/recovery to run the standard
regression tests while a streaming replica replays the WAL.  This
provides a basic workout for WAL decoding and redo code, and compares
the replicated result.

Optionally, enable (expensive) wal_consistency_checking if listed in
the env variable PG_TEST_EXTRA.

Reviewed-by: 綱川 貴之 (Takayuki Tsunakawa) 
Reviewed-by: Andres Freund 
Reviewed-by: Andrew Dunstan 
Reviewed-by: Tom Lane 
Reviewed-by: Anastasia Lubennikova 
Reviewed-by: Michael Paquier 
Discussion: https://postgr.es/m/CA%2BhUKGKpRWQ9SxdxxDmTBCJoR0YnFpMBe7kyzY8SUQk%2BHeskxg%40mail.gmail.com