feat(react-toolkit-form): add a red star on label of required fields

[xballoy]

Automatically add a red star on label of required fields.

Sample render (from storybook):

To migrate from old manual star to new automatic red star:

<TextInput
-  label="My label *"
+  label="My label"
+  classModifier="required"
 {...otherProps}
</TextInput>

cc @guillaume-chervet @samuel-gomez @youf-olivier

[youf-olivier]

Toooooop

[guillaumechervetaxa]

very nice @xballoy :)