Adding PostAction plugin hook (#24102)

* Adding PostAction plugin hook

* Adding missing doc string

* WIP

* Simplifying it

* Adding support for selected text

* fixing linter errors

* Adding support for the plugin editor action in the thread view

* Fixing ci check-types

* Addressing PR review comments

* Fix linter error in CI

* Fixing tests

webapp/channels/src/plugins/registry.ts

@@ -496,6 +496,18 @@ export default class PluginRegistry {
         return id;
     });
 
+    // Register a component to the add to the post message menu shown on hover.
+    // Accepts a React component. Returns a unique identifier.
+    registerPostActionComponent = reArg(['component'], ({component}: DPluginComponentProp) => {
+        return dispatchPluginComponentAction('PostAction', this.id, component);
+    });
+
+    // Register a component to the add to the post text editor menu.
+    // Accepts a React component. Returns a unique identifier.
+    registerPostEditorActionComponent = reArg(['component'], ({component}: DPluginComponentProp) => {
+        return dispatchPluginComponentAction('PostEditorAction', this.id, component);
+    });
+
     // Register a post menu list item by providing some text and an action function.
     // Accepts the following:
     // - text - A string or React element to display in the menu