feat: teach BufferMut into_iter

[danking]

No description provided.

[robert3005]

I would expect the into_iterator to actually consume the buffer instead of copying values

[robert3005]

otherwise you can make &T as a return value and the caller can copy

[gatesn]

I don't understand this, doesn't deref and derefmut give you &T and &mut T iterators already?

[robert3005]

you're correct that it would give you that but I didn't realize deref impls exist before making this comment

[danking]

I want this to compile:

    let buf: BufferMut<T> = values.into_buffer_mut::<T>();
    let mut new_buf: BufferMut<T> = BufferMut::<T>::with_capacity(buf.len() + 1);
    new_buf.push(T::zero());
    new_buf.extend(buf);

But it doesn't because buf does not implement IntoIterator<Item = T>. I somehow want to convince Rust to just memcpy the old buffer into the new buffer.

[robert3005]

You should check out how this is handled for Vec - spoiler alert, you want to be able to introspect passed iterator and extract the buffer back from it.

[danking]

I can punt on all of this and use a for loop because I need to increment each code by one anyway. Erm getting confused between codes and values.

EDIT: Let me look at the Vec implementation and get back to y'all.

[gatesn]

Could you add justification to the PR description?

I can believe this is needed, but I'm not quite sure of the use case to check if it's solvable already somehow