Use function declarations instead of mutating displayName

[nik-rev]

At the moment, shadcn mutates the displayName property directly which can be seen as undesired when we have an alternative to use a function declaration instead.

For example, the FormMessage component currently has this structure:

const FormMessage = React.forwardRef</* Types */>(
  (
    {
      /* Props */
    },
  ) => {
    /* Component */
  },
);
FormMessage.displayName = "FormMessage";

While it could be refactored to use function declaration instead to avoid a mutation:

const FormMessage = React.forwardRef</* Types */>(function FormMessage(
  {
    /* Props */
  },
) {
  /* Component */
});