perf: optimize Zip and ZipBy functions

[d-enk]

• Replace Nth() with NthOrEmpty() to avoid unnecessary error allocation on miss
• Change make(0, size) + append to make(size) + direct assignment
• Use uint for loop indices
• Remove temporary variables in ZipBy functions

This reduces overhead from append operations and structure creation, similar to the Zip5Copy2 optimization pattern.

Reduces code size: +174/-242 lines

[d-enk]

There is probably no need for this

But to improve performance, you can do something like this

func Zip5My2[A, B, C, D, E any](a []A, b []B, c []C, d []D, e []E) []Tuple5[A, B, C, D, E] {
	minSize, maxSize := MinMax(len(a), len(b), len(c), len(d), len(e))

	result := make([]Tuple5[A, B, C, D, E], maxSize)

	index := uint(0)

	_ = a[minSize-1]
	_ = b[minSize-1]
	_ = c[minSize-1]
	_ = d[minSize-1]
	_ = e[minSize-1]

	_ = result[minSize-1]

	for ; index < minSize; index++ {
		result[index].A = a[index]
		result[index].B = b[index]
		result[index].C = c[index]
		result[index].D = d[index]
		result[index].E = e[index]
	}

	for ; index < maxSize; index++ {
		result[index].A = NthOrEmpty(a, index)
		result[index].B = NthOrEmpty(b, index)
		result[index].C = NthOrEmpty(c, index)
		result[index].D = NthOrEmpty(d, index)
		result[index].E = NthOrEmpty(e, index)
	}

	return result
}

[samber]

Why do you mount this into memory?

	_ = a[minSize-1]
	_ = b[minSize-1]
	_ = c[minSize-1]
	_ = d[minSize-1]
	_ = e[minSize-1]

	_ = result[minSize-1]

Is there a Go optimization behind?

[d-enk]

Yeap, it eliminates bounds checking in the next cycle

[samber]

Yes, feel free to create a PR if you see a performance improvement.

(with proper comments to explain the optimizations please!)