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
Migrates us to `coder/websocket` v1.8.12 rather than `nhooyr/websocket` on an older version.
Works around https://github.com/coder/websocket/issues/504 by adding an explicit test for `xerrors.Is(err, io.EOF)` where we were previously getting `io.EOF` from the netConn.
- Adds a new query BatchUpdateLastUsedAt
- Adds calls to BatchUpdateLastUsedAt in app stats handler upon flush
- Passes a stats flush channel to apptest setup scaffolding and updates unit tests to assert modifications to LastUsedAt.
The `SingleTailnet` behavior only checked to see if the `MultiAgent` was
closed, but the websocket error was not being propogated into the
`MultiAgent`, causing it to never be swapped for a new working one.
Fixes https://github.com/coder/coder/issues/11401
Before:
```
Coder Workspace Proxy v0.0.0-devel+85ff030 - Your Self-Hosted Remote Development Platform
Started HTTP listener at http://0.0.0.0:3001
View the Web UI: http://127.0.0.1:3001
==> Logs will stream in below (press ctrl+c to gracefully exit):
2024-01-04 20:11:56.376 [warn] net.workspace-proxy.servertailnet: broadcast server node to agents ...
error= write message:
github.com/coder/coder/v2/enterprise/wsproxy/wsproxysdk.(*remoteMultiAgentHandler).writeJSON
/home/coder/coder/enterprise/wsproxy/wsproxysdk/wsproxysdk.go:524
- failed to write msg: WebSocket closed: failed to read frame header: EOF
```
After:
```
Coder Workspace Proxy v0.0.0-devel+12f1878 - Your Self-Hosted Remote Development Platform
Started HTTP listener at http://0.0.0.0:3001
View the Web UI: http://127.0.0.1:3001
==> Logs will stream in below (press ctrl+c to gracefully exit):
2024-01-04 20:26:38.545 [warn] net.workspace-proxy.servertailnet: multiagent closed, reinitializing
2024-01-04 20:26:38.546 [erro] net.workspace-proxy.servertailnet: reinit multi agent ...
error= dial coordinate websocket:
github.com/coder/coder/v2/enterprise/wsproxy/wsproxysdk.(*Client).DialCoordinator
/home/coder/coder/enterprise/wsproxy/wsproxysdk/wsproxysdk.go:454
- failed to WebSocket dial: failed to send handshake request: Get "http://127.0.0.1:3000/api/v2/workspaceproxies/me/coordinate": dial tcp 127.0.0.1:3000: connect: connection refused
2024-01-04 20:26:38.587 [erro] net.workspace-proxy.servertailnet: reinit multi agent ...
error= dial coordinate websocket:
github.com/coder/coder/v2/enterprise/wsproxy/wsproxysdk.(*Client).DialCoordinator
/home/coder/coder/enterprise/wsproxy/wsproxysdk/wsproxysdk.go:454
- failed to WebSocket dial: failed to send handshake request: Get "http://127.0.0.1:3000/api/v2/workspaceproxies/me/coordinate": dial tcp 127.0.0.1:3000: connect: connection refusedhandshake request: Get "http://127.0.0.1:3000/api/v2/workspaceproxies/me/coordinate": dial tcp 127.0.0.1:3000: connect: connection refused
2024-01-04 20:26:40.446 [info] net.workspace-proxy.servertailnet: successfully reinitialized multiagent agents=0 took=1.900892615s
```
