FIX: Remove unused .as_mut_ptr() on the Array trait
FIX: Remove unused .as_mut_ptr() on the Array trait

Raw pointer taking should go through the MaybeUninit wrappers around the
arrays anyway, when it is partially uninitialized, which it often is.

The remaining .as_ptr() and .as_slice() methods on Array is only used
on a fully initialized array in ArrayString::from_byte_string

bluss/arrayvec