This PR makes it so extensions can provide values for the `language_ids`
method on the `LspAdapter` trait.

These are provided as data in the `language_servers` section of the
`extension.toml`, like so:

```toml
[language_servers.intelephense]
name = "Intelephense"
language = "PHP"
language_ids = { PHP = "php"}
```

Release Notes:

- N/A

Co-authored-by: Max <max@zed.dev>