feat: support PostgreSQL END statement

[olavloite]

Adds support for the PostgreSQL END statement in the Connection API.

See also https://www.postgresql.org/docs/current/sql-end.html

Fixes #2130

[rajatbhatta]

@olavloite: Generally looks good to me except that I have one question. How are we updating the .sql files under main/resources, and test/resources? Do we use any automated way to generate/change these?

[olavloite]

@olavloite: Generally looks good to me except that I have one question. How are we updating the .sql files under main/resources, and test/resources? Do we use any automated way to generate/change these?

Yes, those files are automatically generated from the ClientSideStatements.json file (specifically from the exampleStatements elements in that JSON file). So whenever we add a new (simple) statement to one of these files, we should:

1. Add a number examples for the statement to the JSON file.
2. Run the command listed here. That will generate both valid and invalid statements for the command and add these to the generated SQL test scripts.