Read HLS settings (#39)

from [Zed settings
files](https://zedhub.dev/configuring-zed?highlight=initialization_options#settings-files).

## Example

Set `formatter` to `fourmolu` (default is `ormolu`) via 
- `project` settings in `{project-folder}/.zed/settings.json`
_OR_ 
- `global` settings in `~/.config/zed/settings.json`

```json
  "lsp": {
    "hls": {
      "settings": {
        "haskell": {
          "formattingProvider": "fourmolu",
        },
      },
    },
  },
```

Check [Language-specific server
options](https://haskell-language-server.readthedocs.io/en/latest/configuration.html#language-specific-server-options)
for all possible options. Note that not all options are supported by
Zed.

## Note

`zed_extension_api` needs to be updated to latest `0.7.0` to make
reading `project` settings work. It was already fixed with `0.2.0`.

Author: sectore