Add additional filtering options to pg_waldump.

Add additional filtering options to pg_waldump.

Allow filtering by RelFileNode, BlockNumber, ForkNum and FPW.

Author: David Christensen <david.christensen@crunchydata.com>
Reviewed-by: Japin Li <japinli@hotmail.com>
Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Reviewed-by: Cary Huang <cary.huang@highgo.ca>
Reviewed-by: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://postgr.es/m/lzzgmgm6e5.fsf%40veeddrois.attlocal.net