Fix @kogito-apps/form-displayer issues when establishing the envelope connection

[pefernan]

The @kogito-apps/form-displayer React component is the component in charge of displaying the custom forms generated by the form-generation-tool. This component is embedded by other components like @kogito-apps/task-form & @kogito-apps/form-details.

Due to some recent changes it cannot initialize its envelope accordingly and cannot display any form. Looking at the console there are some logs like:
Failed to execute 'postMessage' on 'Window': Invalid target origin 'null' in a call to 'postMessage'..

Apparently looks like the component isn't getting the right targetOrigin from the parent component that is embeding it.

This error makes the form not able to work fine and causes different issues in task-form and form-details component

Steps to reproduce (for form-details):

1. Generate patternfly forms using form-generation-tool for any BPM Quarkus project in kogito-examples (for example process-usertasks-quarkus-with-console)
2. In the project pom.xml add a dependency to the runtime-tools-quarkus-extension
3. Start the Kogito project in dev mode (mvn clean quarkus:dev)
4. Open the Dev ui (http://locahost:8080/q/dev) and click on the Forms link inside the Runtime Tools Quarkus Extension
5. Once in the forms list, click in any form and you'll be brought to the form-details view, on the left side you'll se a monaco-editor and on the right side the form visualization.
6. Open the console to see the error logs.

Steps to reproduce (for task-form):

1. Generate patternfly forms using form-generation-tool for any BPM Quarkus project in kogito-examples (for example process-usertasks-quarkus-with-console)
2. In the project pom.xml add a dependency to the runtime-tools-quarkus-extension
3. Start the Kogito project in dev mode (mvn clean quarkus:dev)
4. Open the Dev ui (http://locahost:8080/q/dev) and click on the Process Instances link inside the Runtime Tools Quarkus Extension and start a new process instance
5. Jump into Tasks view and switch to the jdoe user to see the tasks assigned to the user.
6. Click on the task... the task form will keep loading forever (same errors in the browser console)