feat: Implement batch processing for stateless processors

[chubei]

Following processors are stateless:

• Projection
• Selection
• Window
• TTL

Following config has the same throughput as without the sql:

app_name: dozer-pg-sample
version: 1
connections:
  - name: dozer_pg_db
    config: !Postgres
      user: chubei
      password: postgres
      host: localhost
      port: 5432
      database: bench_2

sql: SELECT * INTO output FROM pgbench_accounts;

endpoints:
  - table_name: output
    kind: !Dummy

Closes #2311