Feature request: SharedArrayBuffer support

I have published Agda's language service based on WASM. It works fine on VS Code on both desktop and the web ([vscode.dev](https://vscode.dev/github/agda/agda)). On github1s it fails to run due to not cross-origin isolated.

To reproduce:

1. Open https://github1s.com/agda/agda/blob/master/examples/AIM4/bag/Bag.agda.
2. Install `banacorn.agda-mode` and press `Ctrl-C` - `Ctrl-L` to activate the extension.
3. It fails with the following message:

```
Tried to connect with these paths but all failed:
vscode-userdata:/Users/globalStorage/banacorn.agda-mode/dev-als/als.wasm (from DevALS download): WASM connection failed: SharedArrayBuffer is not available in this browser environment. Please serve the web extension with Cross-Origin Opener Policy (COOP) and Cross-Origin Embedder Policy (COEP) headers.
```

I would like to see if it is possible to make github1s cross-origin isolated: https://developer.mozilla.org/en-US/docs/Web/API/Window/crossOriginIsolated by adding COOP and COEP headers to every response under the same origin.