PanelState: Introduce a new separate redux panel state not keyed by panel.id (#40302)

* Initial pass to move panel state to it's own, and make it by key not panel.id

* Progress

* Not making much progress, having panel.key be mutable is causing a lot of issues

* Think this is starting to work

* Began fixing tests

* Add selector

* Bug fixes and changes to cleanup, and fixing all flicking when switching library panels

* Removed console.log

* fixes after merge

* fixing tests

* fixing tests

* Added new test for changePlugin thunk

public/app/features/plugins/importPanelPlugin.ts

@@ -0,0 +1,53 @@
+import config from 'app/core/config';
+import * as grafanaData from '@grafana/data';
+import { getPanelPluginLoadError } from '../panel/components/PanelPluginError';
+import { importPluginModule } from './plugin_loader';
+
+interface PanelCache {
+  [key: string]: Promise<grafanaData.PanelPlugin>;
+}
+const panelCache: PanelCache = {};
+
+export function importPanelPlugin(id: string): Promise<grafanaData.PanelPlugin> {
+  const loaded = panelCache[id];
+  if (loaded) {
+    return loaded;
+  }
+
+  const meta = config.panels[id];
+
+  if (!meta) {
+    throw new Error(`Plugin ${id} not found`);
+  }
+
+  panelCache[id] = getPanelPlugin(meta);
+
+  return panelCache[id];
+}
+
+export function importPanelPluginFromMeta(meta: grafanaData.PanelPluginMeta): Promise<grafanaData.PanelPlugin> {
+  return getPanelPlugin(meta);
+}
+
+function getPanelPlugin(meta: grafanaData.PanelPluginMeta): Promise<grafanaData.PanelPlugin> {
+  return importPluginModule(meta.module)
+    .then((pluginExports) => {
+      if (pluginExports.plugin) {
+        return pluginExports.plugin as grafanaData.PanelPlugin;
+      } else if (pluginExports.PanelCtrl) {
+        const plugin = new grafanaData.PanelPlugin(null);
+        plugin.angularPanelCtrl = pluginExports.PanelCtrl;
+        return plugin;
+      }
+      throw new Error('missing export: plugin or PanelCtrl');
+    })
+    .then((plugin) => {
+      plugin.meta = meta;
+      return plugin;
+    })
+    .catch((err) => {
+      // TODO, maybe a different error plugin
+      console.warn('Error loading panel plugin: ' + meta.id, err);
+      return getPanelPluginLoadError(meta, err);
+    });
+}