Add code block actions plugin extensibility (#24348)

* Add code block actions plugin extensibility

* Fixing tests

* Fixing linter errors

* Move Plugin components left of label

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Co-authored-by: Christopher Speller <crspeller@gmail.com>

webapp/channels/src/plugins/registry.ts

@@ -508,6 +508,12 @@ export default class PluginRegistry {
         return dispatchPluginComponentAction('PostEditorAction', this.id, component);
     });
 
+    // Register a component to the add to the code block header.
+    // Accepts a React component. Returns a unique identifier.
+    registerCodeBlockActionComponent = reArg(['component'], ({component}: DPluginComponentProp) => {
+        return dispatchPluginComponentAction('CodeBlockAction', this.id, component);
+    });
+
     // Register a component to the add to the new messages separator.
     // Accepts a React component. Returns a unique identifier.
     registerNewMessagesSeparatorActionComponent = reArg(['component'], ({component}: DPluginComponentProp) => {