chore: add support for one-way websockets to backend (#16853)

Closes https://github.com/coder/coder/issues/16775

## Changes made
- Added `OneWayWebSocket` function that establishes WebSocket
connections that don't allow client-to-server communication
- Added tests for the new function
- Updated API endpoints to make new WS-based endpoints, and mark
previous SSE-based endpoints as deprecated
- Updated existing SSE handlers to use the same core logic as the new WS
handlers

## Notes
- Frontend changes handled via #16855

docs/reference/api/schemas.md

@@ -5735,6 +5735,38 @@ Git clone makes use of this by parsing the URL from: 'Username for "https://gith
 | `ssh_config_options` | object | false    |              |             |
 | » `[any property]`   | string | false    |              |             |
 
+## codersdk.ServerSentEvent
+
+```json
+{
+  "data": null,
+  "type": "ping"
+}
+```
+
+### Properties
+
+| Name   | Type                                                         | Required | Restrictions | Description |
+|--------|--------------------------------------------------------------|----------|--------------|-------------|
+| `data` | any                                                          | false    |              |             |
+| `type` | [codersdk.ServerSentEventType](#codersdkserversenteventtype) | false    |              |             |
+
+## codersdk.ServerSentEventType
+
+```json
+"ping"
+```
+
+### Properties
+
+#### Enumerated Values
+
+| Value   |
+|---------|
+| `ping`  |
+| `data`  |
+| `error` |
+
 ## codersdk.SessionCountDeploymentStats
 
 ```json

docs/reference/api/workspaces.md

@@ -1979,3 +1979,41 @@ curl -X GET http://coder-server:8080/api/v2/workspaces/{workspace}/watch \
 | 200    | [OK](https://tools.ietf.org/html/rfc7231#section-6.3.1) | OK          | [codersdk.Response](schemas.md#codersdkresponse) |
 
 To perform this operation, you must be authenticated. [Learn more](authentication.md).
+
+## Watch workspace by ID via WebSockets
+
+### Code samples
+
+```shell
+# Example request using curl
+curl -X GET http://coder-server:8080/api/v2/workspaces/{workspace}/watch-ws \
+  -H 'Accept: application/json' \
+  -H 'Coder-Session-Token: API_KEY'
+```
+
+`GET /workspaces/{workspace}/watch-ws`
+
+### Parameters
+
+| Name        | In   | Type         | Required | Description  |
+|-------------|------|--------------|----------|--------------|
+| `workspace` | path | string(uuid) | true     | Workspace ID |
+
+### Example responses
+
+> 200 Response
+
+```json
+{
+  "data": null,
+  "type": "ping"
+}
+```
+
+### Responses
+
+| Status | Meaning                                                 | Description | Schema                                                         |
+|--------|---------------------------------------------------------|-------------|----------------------------------------------------------------|
+| 200    | [OK](https://tools.ietf.org/html/rfc7231#section-6.3.1) | OK          | [codersdk.ServerSentEvent](schemas.md#codersdkserversentevent) |
+
+To perform this operation, you must be authenticated. [Learn more](authentication.md).