Rollup merge of #94667 - frank-king:feature/iter_map_windows, r=Mark-Simulacrum

Add `Iterator::map_windows`

Tracking issue:  #87155.

This is inherited from the old PR  #82413.

Unlike #82413, this PR implements the `MapWindows` to be lazy: only when pulling from the outer iterator, `.next()` of the inner iterator will be called.

## Implementaion Steps
- [x] Implement `MapWindows` to keep the iterators' [*Laziness*](https://doc.rust-lang.org/std/iter/index.html#laziness) contract.
- [x] Fix the known bug of memory access error.
- [ ] Full specialization of iterator-related traits for `MapWindows`.
    - [x] `Iterator::size_hint`,
    - [x] ~`Iterator::count`~,
    - [x] `ExactSizeIterator` (when `I: ExactSizeIterator`),
    - [x] ~`TrustedLen` (when `I: TrustedLen`)~,
    - [x] `FusedIterator`,
    - [x] ~`Iterator::advance_by`~,
    - [x] ~`Iterator::nth`~,
    - [ ] ...
- [ ] More tests and docs.

## Unresolved Questions:
- [ ] Is there any more iterator-related traits should be specialized?
- [ ] Is the double-space buffer worth?
- [ ] Should there be `rmap_windows` or something else?
- [ ] Taking GAT for consideration, should the mapper function be `FnMut(&[I::Item; N]) -> R` or something like `FnMut(ArrayView<'_, I::Item, N>) -> R`? Where `ArrayView` is mentioned in https://github.com/rust-lang/generic-associated-types-initiative/issues/2.
    - It can save memory, only the same size as the array window is needed,
    - It is more efficient, which requires less data copies,
    - It is possibly compatible with the GATified version of `LendingIterator::windows`.
    - But it prevents the array pattern matching like `iter.map_windows(|_arr: [_; N]| ())`, unless we extend the array pattern to allow matching the `ArrayView`.

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