This PR extracts Deno support into an extension and removes the built-in
Deno support from Zed.
When using the Deno extension, you'll want to add the following to your
settings to disable the built-in TypeScript and ESLint language servers
so that they don't conflict with Deno's functionality:
```json
{
"languages": {
"TypeScript": {
"language_servers": ["deno", "!typescript-language-server", "!eslint", "..."]
},
"TSX": {
"language_servers": ["deno", "!typescript-language-server", "!eslint", "..."]
}
}
}
```
Release Notes:
- Removed built-in support for Deno, in favor of making it available as
an extension.
