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>
This PR extracts PHP support into an extension and removes the built-in
PHP support from Zed.
There's a small workaround necessary in order for us to provide the
`language_ids` on the `LspAdapter` that are needed for the language
server to run properly. Eventually we'll want to build this into the
extension API, but for now we're just hard-coding it on the host side.
Release Notes:
- Removed built-in support for PHP, in favor of making it available as
an extension. The PHP extension will be suggested for download when you
open a `.php` file.
