Error state can only be applied to the entire radio button group

[B3nz01d]

In the Radio Button > Variant > Outline example, the radio button group shows one example of the error in the group. This should never be the case.

The current exemple should be split into 2 examples:

• one showing the same element with the last one without the error
• one added under the "Invalid" section, named "Invalid Outlined" where it would be the same but with all items set to Invalid

[MaxLardenois]

After discussion with Maxime, we will add a sub-paragraph in the Invalid state with the outlined option.