[zig] fix arrays iterations with indexes

[p1k0chu]

fix for loops with indexes and pointers, commit messages have detailed info:

[zig] fix arrays iterations with indexes

the syntax `for (array) | value, i | {}` gives compile time error
for an extra capture group

you need to add another iterable like 0.. for this to work

also added a simple for loop over multiple iterables
to demostrate this
---
[zig] fix array iteration with pointers

this syntax iterates over an array of pointers
```
for (items) |*value| {}
```
and crashes if you iterate over a normal array like [_]i32

to capture a pointer to an array item itself, this is correct:
```
var items = [_]i32{...};
for (&items) |*value| {}
```

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[vendethiel]

Thanks!