feat: Allow to set a database to connect to in a script

[CharlesDelannoy]

Add database parameter to postgresql_script resource

Summary

Adds an optional database parameter to postgresql_script to specify which database to execute commands in. Defaults to the provider's configured database for backwards compatibility.

Changes

• Added database schema field (optional, computed)
• Updated connection logic to use getDatabase() helper and create new connection if needed
• Refactored to call ReadImpl() at end of Create/Update (matches pattern used by postgresql_schema)

Usage

resource "postgresql_script" "app_schema" {
  database = "myapp"
  commands = ["CREATE TABLE users (id INT)"]
}

Breaking Changes

None - fully backwards compatible.

FOR REVIEWERS

I did not close explicitely the connection because tests was failling due to Error: Commands execution failed .... sql: database is closed
It seems that for a DB the provider need to be able to reuse a connection pool that is cached for further operation. So if we close the connection we have issue for further connections

[CharlesDelannoy]

@bpaquet I added a section on the description but tldr: we should not close the db connection as it may be reused if connecting to the same db. It seems the provider handle this on his side