fix: re-enable support for wasm targets

[sdd]

• The implementation of within_unsorted_iter on v3.0.0 made use of the generator crate, which only supports x86_64 and aarch64. The within_unsorted_iter methods have been made conditional, only being compiled on x86_64 or aarch64, so that the rest of the library works on other target architectures.

[codecov-commenter]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (b68e499) 92.45% compared to head (d068c26) 92.40%.

Files	Patch %	Lines
src/fixed/query/within_unsorted_iter.rs	0.00%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #125 +/- ## ========================================== - Coverage 92.45% 92.40% -0.05% ========================================== Files 51 51 Lines 6188 6190 +2 Branches 6188 6190 +2 ========================================== - Hits 5721 5720 -1 - Misses 437 440 +3 Partials 30 30 ```

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