refactor: create new `queryopt` package to target query plan optimizations #10472

Job	Run time
paths-filter	42s
E2E (22.1.5)	1m 58s
Steelthread	5m 7s
Analyzers Unit Tests	2m 11s
Unit	11m 39s
Build Binary & Image	4m 56s
Datastore Consistency Tests (mysql)	4m 3s
Datastore Integration Tests (mysql)	3m 15s
Datastore Consistency Tests (postgres, 17)	2m 29s
Integration Tests	10m 0s
Datastore Consistency Tests (crdb, 26.1.0)	3m 23s
Datastore Integration Tests (spanner)	5m 57s
Run Go benchmarks	14m 16s
Datastore Consistency Tests (postgres, 16)	2m 10s
Datastore Integration Tests (crdb, 25.2.0)	10m 38s
Datastore Consistency Tests (crdb, 25.2.0)	3m 29s
Datastore Consistency Tests (spanner)	2m 14s
Datastore Integration Tests (crdb, 26.1.0)	10m 7s
Datastore Consistency Tests (postgres, 15)	2m 11s
Datastore Consistency Tests (postgres, 18)	2m 8s
WASM Tests	1m 13s
Datastore Integration Tests (pgbouncer, 18)	3m 10s
Datastore Integration Tests (postgres, 17)	2m 57s
Datastore Integration Tests (pgbouncer, 14)	3m 28s
Datastore Integration Tests (postgres, 14)	3m 20s
Datastore Integration Tests (postgres, 18)	3m 6s
Datastore Integration Tests (pgbouncer, 17)	3m 19s
Datastore Consistency Tests (postgres, 14)	2m 10s
Datastore Integration Tests (postgres, 15)	3m 2s
Datastore Integration Tests (pgbouncer, 15)	3m 14s
Datastore Integration Tests (postgres, 16)	3m 27s
Datastore Integration Tests (pgbouncer, 16)	3m 27s
Generate Protobufs	0s
	2h 18m 46s

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