Remove Beancount as a built-in language (#7934)

This PR removes Beancount as a built-in language, as it is now available
as an [extension](https://github.com/zed-extensions/beancount).

Release Notes:

- Removed built-in support for Beancount, as it is now provided by an
[extension](https://github.com/zed-extensions/beancount).
b91d6da6b6Marshall Bowers committed on 2/18/2024, 2:58:12 PM· committed by GitHubparenta041e07
6 files changedLine totals unavailable