feat(agent): add container list handler (#16346)

Fixes https://github.com/coder/coder/issues/16268

- Adds `/api/v2/workspaceagents/:id/containers` coderd endpoint that allows listing containers
visible to the agent. Optional filtering by labels is supported.
- Adds go tools to the `coder-dylib` CI step so we can generate mocks if needed

coderd/coderd.go

@@ -1211,6 +1211,7 @@ func New(options *Options) *API {
 				r.Get("/logs", api.workspaceAgentLogs)
 				r.Get("/listening-ports", api.workspaceAgentListeningPorts)
 				r.Get("/connection", api.workspaceAgentConnection)
+				r.Get("/containers", api.workspaceAgentListContainers)
 				r.Get("/coordinate", api.workspaceAgentClientCoordinate)
 
 				// PTY is part of workspaceAppServer.