feat(corelib): add RangeBounds and Bound

[cairoIover]

With the addition of new range operators and range types (WIP in #6972) , we are going to have different kinds of bounds for ranges.

Implements the Bound enum (representing all 3 kinds of possible bounds) and the RangeBounds associated trait to get the bounds of a range.

Later this will be useful to abstract some inner impls (like whether a range contains a number or not) an use a single common implementation.

I left out some comments regarding internal bugs to discuss.

[reviewable-StarkWare]

This change is 

[orizi]

if it is useful only for contains i rather just have an implementation for contains.

Reviewable status: 0 of 3 files reviewed, 1 unresolved discussion (waiting on @cairoIover)

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corelib/src/ops/range.cairo line 263 at r1 (raw file):

                Bound::Excluded(end) => item < end,
                Bound::Unbounded => true,
            })

implementing the basic implementation is more efficient.

Suggestion:

        start <= item && item < end

[cairoIover]

understandable. I was thinking it would be interesting to make reasoning for contains based on bounds types, but we can also go for simplicity and avoid abstractions. I can close

Reviewable status: 0 of 3 files reviewed, 1 unresolved discussion (waiting on @orizi)

[orizi]

until we find further use cases - i think this is preferable.

Reviewable status: 0 of 3 files reviewed, 1 unresolved discussion (waiting on @cairoIover)