Modal Button Title and close behavior

Part one was done in dev release.
It is still open, to not close/remove context of sidekick when closing sidekick in modal window)

Since yesterday afternoon I've been investigating the modal persistence issue, I'm embarrassed to say how long it took me to realise that the controller returning the AJAX response is where the dialog options are parsed.

Now that I finally found where to control the behaviour, I plan to update it.

On clicking the 'Open Sidekick' button:
- the button should load the iframe and insert it onto the page
- the button should be updated so it toggles the visibility of the iframe

I'll dive in to this topic to figure out how to achieve this in D10: https://www.drupal.org/docs/drupal-apis/ajax-api/core-ajax-callback-comm... →

Update: I will need to add some js code to the sidekick_js library to prevent the default close actions.