feat(corelib): Impl fmt::debug for Range

[julio4]

Formats a Range type, allowing to print Range instances for debugging purposes.

Example

println!("{:?}", 1..5); // Result will be `1..5`

[reviewable-StarkWare]

This change is 

[orizi]

Reviewed 1 of 3 files at r1.
Reviewable status: 1 of 3 files reviewed, 1 unresolved discussion (waiting on @julio4)

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corelib/src/test/range_test.cairo line 3 at r1 (raw file):

#[test]
fn test_range_format() {
    assert(format!("{:?}", 1..5) == "1..5", 'bad range debug formatting');

Suggestion:

    assert!(format!("{:?}", 1..5) == "1..5");

[julio4]

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

---

corelib/src/test/range_test.cairo line 3 at r1 (raw file):

#[test]
fn test_range_format() {
    assert(format!("{:?}", 1..5) == "1..5", 'bad range debug formatting');

Done.

[orizi]

Reviewed 1 of 3 files at r1, all commit messages.
Reviewable status: 2 of 3 files reviewed, all discussions resolved

---

a discussion (no related file):
@gilbens-starkware for 2nd eye.

[gilbens-starkware]

Reviewable status: 2 of 3 files reviewed, all discussions resolved (waiting on @orizi)

[orizi]

Reviewed 1 of 1 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @julio4)