refactor: replace CStr::from_ptr(ptr).to_str() with from_utf8_unchecked

[legendiguess]

closes #53

[codecov]

Codecov Report

Merging #66 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #66      +/-   ##
==========================================
- Coverage   72.09%   72.09%   -0.01%     
==========================================
  Files         109      109              
  Lines        7279     7278       -1     
==========================================
- Hits         5248     5247       -1     
  Misses       2031     2031

Impacted Files	Coverage Δ
crates/mun_abi/src/autogen_impl.rs	98.42% <100%> (-0.01%)	⬇️
crates/mun_target/src/spec/windows_msvc_base.rs	100% <0%> (ø)	⬆️
...ates/mun_target/src/spec/x86_64_pc_windows_msvc.rs	100% <0%> (ø)	⬆️
crates/mun_codegen/src/code_gen/linker.rs	35.63% <0%> (ø)	⬆️

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[Wodann]

Thank you for you PR. Good find to reuse the CStr::from_ptr function to convert a null-terminated C-style string into a u8 slice 👍

I added one request for change, as we only need to replace the UTF-8 validation in the ABI. If you could revert the changes to crates/mun_runtime_capi/src/lib.rs that'd be great :)

There is one other thing that needs to happen before we can merge this PR. Issue #53 depends on issue #52. That issue adds unit tests to validate that our compiler always generates valid UTF-8 strings. Once that issue has been closed, we can guarantee that there will not be any runtime regressions. If you have time, would you be interested in having a look at issue #52 as well? It will introduce you to an important development aspect of Mun; namely regression testing.

[Wodann]

Thank you for the improvements. It all looks good now.

I'll still hold on merging until issue #52 has been resolved.