Notify existing Community Extensions of changed API

The updated extension API entrypoint from DuckDB v1.4 will require some work from many community extension maintainers. We'll automatically create an issue in the affected repositories pointing to this issue.

The easiest way to understand what needs to change is to look at the [extension template PR](https://github.com/duckdb/extension-template/pull/132) that applies the changes.

If you want to prepare your extension before the DuckDB v1.4.0 is out, check out this example on how to use `ref_next` in the PR where the quack extension is bumped: https://github.com/duckdb/community-extensions/pull/548

Start with the extension template PR #132, which shows the required DuckDB v1.4 API changes, then compare the ref_next usage in the quack bump PR #548. The issue's stated outcome is to notify affected community extension repositories, but it does not identify an implementation file, test, or a self-contained change for this repository.

Written by the indexing model from the issue text.