improve inferrability of tuple slicing (#39074)
* RFC: improve inferrability of tuple slicing
This makes slicing tuples type stable in a lot more cases. This now only calls `ntuple` if the resulting tuple has no more than 10 elements, as just relying on the fallback in `ntuple` did have some compile-time overhead in my artificial benchmarks. I also widened the signature to `AbstractUnitRange`, since I don't see why we shouldn't have this for ranges like `OneTo` as well.
* add check for offset ranges and more tests
* add guard if OffsetArrays is already imported
Co-authored-by: Matt Bauman <mbauman@juliacomputing.com>
* import OffsetArrays correctly
Co-authored-by: Matt Bauman <mbauman@juliacomputing.com>
