Allow user to use multiple formatters (#14846)

Fixes #4822
- [x] Release note
- [ ] Surface formatting errors via a toast
- [x] Doc updates
- [x] Have "language-server" accept an optional name of the server.

Release Notes:

- `format` and `format_on_save` now accept an array of formatting
actions to run.
- `language_server` formatter option now accepts the name of a language
server to use (e.g. `{"language_server": {"name: "ruff"}}`); when not
specified, a primary language server is used.

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Co-authored-by: Thorsten <thorsten@zed.dev>