[ic-date-input/picker]: Add 'hideHelperText' prop

@GCHQ-Developer-299 is already working on this.

Since Aug 7, 2024.

## Summary
By default, the date input/picker displays helper text'. This ticket is to create a prop which removes the helper text.

## 💬 Description
By default, the date input/picker displays helper text'. Some designs may not require help text as the placeholders for picker/input present the required format. If custom helper text is required, there is no need to remove the helper text. The solution is to create a simple 'hideHelperText' prop to hide it.

In terms of a11y, the format is announced by screen readers so there should not be an issue. The announcement is made via labelledby so it may be better to add 'sr-only' class to the helper text instead of removing the element from the DOM.

## 💰 Use value
Add extra flexibility to the visual for input/picker as some designs may not use helper text for form controla.

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

*Given as a developer*
*When I set 'hideHelperText' prop to true*
*Then the helper text should disappear visually but still be read out by screen readers*

## ✏ Designs
N/A

## 🧾 Guidance
N/A

## Additional info
The helper text within the doc returns 'undefined' as the custom helper text value. This needs to be changed to 'Use format '. This is a small update which can be added to this ticket.