pg_dump: Add --schema-no-create option [PG17]

[NanoBjorn]

Adds a new --schema-no-create option to pg_dump that allows dumping schema data without generating CREATE SCHEMA statements. When this option is used, the specified schema is automatically included in the dump but the schema creation statement is skipped, allowing data to be imported into existing schemas.

This option is used by the Neon fast import feature (PR #11908) to allow migrations of only objects in certain schemas.

Usage: pg_dump --schema-no-create=schema_name database_name

[MMeent]

Can't you just filter CREATE SCHEMA statements from the output?

[MMeent]

Unrelated to the above: please use --no-<option-name> instead of --<option>-no-<name>, as that is easier to understand.