Support handling deeplinks in plugins

Summary:
This adds support for handling incoming deeplinks in a Sandy plugin, which can be done by using a `client.onDeepLink(deepLink => { } )` listener

Also generalized deeplinks to not just support strings, but also richer objects, which is beneficial to plugin to plugin linking.

Reviewed By: jknoxville

Differential Revision: D22524749

fbshipit-source-id: 2cbe8d52f6eac91a1c1c8c8494706952920b9181

desktop/app/src/PluginContainer.tsx

@@ -101,7 +101,7 @@ type StateFromProps = {
   activePlugin: PluginDefinition | undefined;
   target: Client | BaseDevice | null;
   pluginKey: string | null;
-  deepLinkPayload: string | null;
+  deepLinkPayload: unknown;
   selectedApp: string | null;
   isArchivedDevice: boolean;
   pendingMessages: Message[] | undefined;
@@ -113,7 +113,7 @@ type DispatchFromProps = {
   selectPlugin: (payload: {
     selectedPlugin: string | null;
     selectedApp?: string | null;
-    deepLinkPayload: string | null;
+    deepLinkPayload: unknown;
   }) => any;
   setPluginState: (payload: {pluginKey: string; state: any}) => void;
   setStaticView: (payload: StaticView) => void;
@@ -178,6 +178,13 @@ class PluginContainer extends PureComponent<Props, State> {
 
   componentDidUpdate() {
     this.processMessageQueue();
+    // make sure deeplinks are propagated
+    const {deepLinkPayload, target, activePlugin} = this.props;
+    if (deepLinkPayload && target instanceof Client && activePlugin) {
+      target.sandyPluginStates
+        .get(activePlugin.id)
+        ?.triggerDeepLink(deepLinkPayload);
+    }
   }
 
   processMessageQueue() {
@@ -373,7 +380,7 @@ class PluginContainer extends PureComponent<Props, State> {
         setPersistedState: (state) => setPluginState({pluginKey, state}),
         target,
         deepLinkPayload: this.props.deepLinkPayload,
-        selectPlugin: (pluginID: string, deepLinkPayload: string | null) => {
+        selectPlugin: (pluginID: string, deepLinkPayload: unknown) => {
           const {target} = this.props;
           // check if plugin will be available
           if (