feat: add shouldHaveSingleInstancePerWholeApp method to AdminForthPlugin interface and implementations

Author: yaroslav8765

adminforth/basePlugin.ts

@@ -36,6 +36,10 @@ export default class AdminForthPlugin implements IAdminForthPlugin {
     return 'non-uniquely-identified';
   }
 
+  shouldHaveSingleInstancePerWholeApp(): boolean {
+    return true;
+  }
+
   modifyResourceConfig(adminforth: IAdminForth, resourceConfig: AdminForthResource, allPluginInstances?: {pi: AdminForthPlugin, resource: AdminForthResource}[]) {
     this.resourceConfig = resourceConfig;
     const uniqueness = this.instanceUniqueRepresentation(this.pluginOptions);

adminforth/commands/createPlugin/templates/index.ts.hbs

@@ -27,6 +27,10 @@ export default class {{pluginName}} extends AdminForthPlugin {
     return `single`;
   }
 
+  shouldHaveSingleInstancePerWholeApp(): boolean {
+    return false;
+  }
+
   setupEndpoints(server: IHttpServer) {
     server.endpoint({
       method: 'POST',

adminforth/types/Back.ts

@@ -468,6 +468,13 @@ export interface IAdminForthPlugin {
   instanceUniqueRepresentation(pluginOptions: any) : string;
 
 
+  /**   
+   * If this method returns true, AdminForth will allow only one instance of plugin per whole app
+   * (only for case when we are creating copy of resource and activating plugins)
+   * If false, multiple instances of plugin can be installed on different resources.
+   */
+  shouldHaveSingleInstancePerWholeApp(): boolean;
+
   /**
    * Optional method which will be called after AdminForth discovers all resources and their columns.
    * Can be used to validate types of columns, check if some columns are missing, etc.