Change .reduce to for...of loop to improve performance

[fabian-hiller]

In several places, for example in partial, we currently still use .reduce. For performance reasons, it may make sense to change this to a for...of loop. Since we use for...of in several other places in the library, this change should not affect the bundle size due to compression and should make the code more consistent.

Idea for this change comes from @kurtextrem in #202

[lo1tuma]

Is the usage of .reduce really a bottleneck in applications that use valibot? I usually recommend to avoid micro-optimizations, especially when it is about language features, because the performance could change with every new release of the engine (e.g. v8).
So I think a data-driven approach would be better. E.g. having a benchmark suite, which tests the real-world usage of valibot. This could then be used to identify the performance bottlenecks. Optimizing something that is not the bottleneck is usually waste or in the worst case it increases the complexity or maintainability of the codebase without any benefits.

[fabian-hiller]

Thank you for your feedback! I will take it into consideration. We plan to add performance benchmarks to our CI in #100.