handle arbitrary slice types in sort builtin

[netliomax25-code]

sort only special-cases []any/[]int/[]float64/[]string, so a dynamically typed slice like []int64 or []uint falls through the switch and returns an empty slice with no error, silently dropping every element. Handle any slice or array through reflection like reverse and uniq do.

[antonmedv]

looks like a lot of generated expressions now are falling

[netliomax25-code]

Yeah, the error path was too broad. sort used to silently return empty for anything that wasn't one of the special-cased slice types, so the generated corpus has a bunch of expressions sorting maps/nil/struct slices that relied on that. Dropped the error and narrowed the reflection fallback to only pick up slices/arrays whose element kind is actually orderable (ints, uints, floats, string, bool). Everything else keeps the old no-op behavior. gen tests are green again.