PG-545: pg_stat_monitor: Same query text should generate same queryid

Regardless of the database or the user, the same query will yield the
same query ID. As part of this, a new column, 'pgsm_query_id', is added.

* pgsm_query_id:
pgsm_query_id has the same data type of int8 as the queryid column. If
the incoming SQL command includes any constants, it internally normalizes
the query to remove those constant values with placeholders. Otherwise,
it uses the query directly to generate the query hash.

Since we no longer depend on the server's parse tree mechanism, we can
generate the same hash for the same query text for all server versions.

Also, it is important to note that the hash being calculated is a database,
schema and user independent. So same query text in different databases
will generate the same hash.

This column is not part of the key; rather, for observability purposes only.

* Regression
SQL test case pgsm_query_id.sql is added to the SQL regression.

pg_stat_monitor.h

@@ -319,6 +319,7 @@ typedef struct Counters
 typedef struct pgssEntry
 {
 	pgssHashKey key;			/* hash key of entry - MUST BE FIRST */
+	uint64		pgsm_query_id;	/* pgsm generate normalized query hash */
 	Counters	counters;		/* the statistics for this query */
 	int			encoding;		/* query text encoding */
 	slock_t		mutex;			/* protects the counters only */