Function implicit_bit_string 

pub fn implicit_bit_string<'a>(
    parent: &Reader<'a>,
    element: &Element<'a>,
    field: &'static str,
) -> Result<()>

Validates the contents of a schema-selected IMPLICIT BIT STRING. The enclosing schema checks its context tag; this reuses the same iterative BER fragment/padding kernel as universal BIT STRINGs. DER requires primitive.