Replace HICTK_UNREACHABLE_CODE macro with hictk::unreachable_code()

[robomics]

[no ci]

[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 2 lines in your changes missing coverage. Please review.

Project coverage is 79.29%. Comparing base (5e298f6) to head (ece59da).
Report is 25 commits behind head on main.

Files with missing lines	Patch %	Lines
src/libhictk/hic/include/hictk/hic/common.hpp	0.00%	1 Missing ⚠️
...k/hic/include/hictk/hic/impl/block_reader_impl.hpp	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #285      +/-   ##
==========================================
+ Coverage   79.04%   79.29%   +0.25%     
==========================================
  Files         171      173       +2     
  Lines       16327    16995     +668     
  Branches     2251     2309      +58     
==========================================
+ Hits        12906    13477     +571     
- Misses       2454     2514      +60     
- Partials      967     1004      +37     

Flag	Coverage Δ
[tests	integration](https://app.codecov.io/gh/paulsengroup/hictk/pull/285/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=paulsengroup)	69.75% <33.33%> (+0.19%)
[tests	unittests](https://app.codecov.io/gh/paulsengroup/hictk/pull/285/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=paulsengroup)	77.31% <33.33%> (+0.88%)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.