Implement manhattan and chebyshev distance for integer vectors

[tguichaoua]

This implements #415 using the code generator.

[bitshifter]

Thanks for the PR.

abs_diff on signed integers returns an unsigned integer so this will need a bit more work to code generate that .

The original #415 PR returned the result in a larger sized integer which for the Manhattan distance would help avoid overflow, however I guess for higher dimensions than 2 overflow would still be possible, so I'm not sure it's worth doing that. Also while glam doesn't currently have a I128Vec* or U128Vec* if they're ever added there is no u256 primitive in Rust which would make returning a larger integer in with any 128 sizes integer vector not possible. Give that I'm leaning towards your implementation and not returning a larger integer type, but adding a comment to the method pointing out that the result could overflow so that the caller is aware. Do you have any thoughts on how overflow should be handled for these?

Could you also add some tests for these new methods as part of this PR.

[tguichaoua]

Do you have any thoughts on how overflow should be handled for these?

We should use unsigned integer as return type. As per the documentation of abs_diff:

This function always returns the correct answer without overflow or panics by returning an unsigned integer.

For manhattan_distance I added checked_manhattan_distance which returns None if an overflow would occurs.

[bitshifter]

Thanks!