Fix kubeconfig-sync issues (#2692)

- Removed `getFreePort` as its use is always a race condition. Change
  all uses of it to retrive the port after listening

- Added `getPortFrom` as a helper function to read a port from a stream

- Remove `Cluster.ownerRef` as it is outdated and no longer needed for 5.0

- Remove `Cluster.enabled`, no longer needed because of above

- Removed `Cluster.init`, moved its contents into `Cluster.constructor`
  as nothing in that function is asyncronous. Currently only being run
  on `main` as a stop gap until `renderer` gets its own version of
  `Cluster`

- Refactored `LensProxy` so as to prevent `pty.node` (a NodeJS
  extension) being included in `webpack.extension.ts`'s run

- Removed the passing around of the proxy port as that can now be
  accessed from an instance of `LensProxy`

- purge ContextHandler's cache on disconnect

Co-authored-by: Sebastian Malton <sebastian@malton.name>

src/main/k8s-request.ts

@@ -0,0 +1,29 @@
+import request, { RequestPromiseOptions } from "request-promise-native";
+import { apiKubePrefix } from "../common/vars";
+import { IMetricsReqParams } from "../renderer/api/endpoints/metrics.api";
+import { LensProxy } from "./proxy/lens-proxy";
+import { Cluster } from "./cluster";
+
+export async function k8sRequest<T = any>(cluster: Cluster, path: string, options: RequestPromiseOptions = {}): Promise<T> {
+  const kubeProxyUrl = `http://localhost:${LensProxy.getInstance().port}${apiKubePrefix}`;
+
+  options.headers ??= {};
+  options.json ??= true;
+  options.timeout ??= 30000;
+  options.headers.Host = `${cluster.id}.${new URL(kubeProxyUrl).host}`; // required in ClusterManager.getClusterForRequest()
+
+  return request(kubeProxyUrl + path, options);
+}
+
+export async function getMetrics(cluster: Cluster, prometheusPath: string, queryParams: IMetricsReqParams & { query: string }): Promise<any> {
+  const prometheusPrefix = cluster.preferences.prometheus?.prefix || "";
+  const metricsPath = `/api/v1/namespaces/${prometheusPath}/proxy${prometheusPrefix}/api/v1/query_range`;
+
+  return k8sRequest(cluster, metricsPath, {
+    timeout: 0,
+    resolveWithFullResponse: false,
+    json: true,
+    method: "POST",
+    form: queryParams,
+  });
+}