feat: show service banner in SSH/TTY sessions (#8186)

* Allow workspace agents to get appearance
* Poll for service banner every two minutes
* Show service banner before MOTD if not quiet

coderd/httpmw/actor.go

@@ -35,3 +35,32 @@ func RequireAPIKeyOrWorkspaceProxyAuth() func(http.Handler) http.Handler {
 		})
 	}
 }
+
+// RequireAPIKeyOrWorkspaceAgent is middleware that should be inserted after
+// optional ExtractAPIKey and ExtractWorkspaceAgent middlewares to ensure one of
+// the two is provided.
+//
+// If both are provided an error is returned to avoid misuse.
+func RequireAPIKeyOrWorkspaceAgent() func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			_, hasAPIKey := APIKeyOptional(r)
+			_, hasWorkspaceAgent := WorkspaceAgentOptional(r)
+
+			if hasAPIKey && hasWorkspaceAgent {
+				httpapi.Write(r.Context(), w, http.StatusBadRequest, codersdk.Response{
+					Message: "API key and workspace agent token provided, but only one is allowed",
+				})
+				return
+			}
+			if !hasAPIKey && !hasWorkspaceAgent {
+				httpapi.Write(r.Context(), w, http.StatusUnauthorized, codersdk.Response{
+					Message: "API key or workspace agent token required, but none provided",
+				})
+				return
+			}
+
+			next.ServeHTTP(w, r)
+		})
+	}
+}