[IcTextField] - icon not rendered if slot initially empty

[ad9242]

Summary of the bug

If a textfield initially has no icon, but one is subsequently added, the icon is not visible

🪜 How to reproduce

With the following stackblitz example

When clicking the button, the visibility of the icon should change It does work if the icon is initially visible

🧐 Expected behaviour

The icon should be visible when the slot has content

📝 Acceptance Criteria

If relevant, describe in full detail the different interactions and edge cases that the component or patterns needs to fulfil.

Given an icon slot in a textfield is empty When adding an icon to the slot Then the icon should be visible

Given an icon is visible in a textfield When removing the slot content Then the icon should not be visible

Additional info

This is closely linked to #1867