Replace uses of unsafe with safe alternatives

[nabilwadih]

Some of the usages of unsafe in the codebase can now be replaced with safe functions from the rust standard library. This PR updates those to remove the unsafe blocks

Verified that all of the tests are still passing.

[Geal]

these unsafe calls are there to avoid paying anohter bounds check (and for &str a is_char_boundary check) while code outside is already supposed to guarantee it

[codspeed-hq]

CodSpeed Performance Report

Merging #1714 will not alter performance

_{Comparing nabilwadih:nwadih/removeUnsafe (5ec2746) with main (cdd8baf)}

Summary

✅ 24 untouched benchmarks

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 62.01%. Comparing base (cdd8baf) to head (5ec2746).

Files	Patch %	Lines
src/traits.rs	80.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1714      +/-   ##
==========================================
- Coverage   62.01%   62.01%   -0.01%     
==========================================
  Files          24       24              
  Lines        2912     2917       +5     
==========================================
+ Hits         1806     1809       +3     
- Misses       1106     1108       +2     

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[Geal]

running the benchmarks again, this has no noticeable impact, so this will be ok