Improve GNU compatibility of a, c, i commands

[dspinellis]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 59 lines in your changes missing coverage. Please review.
✅ Project coverage is 0.00%. Comparing base (fdd5c42) to head (9f679cd).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
src/uu/sed/src/compiler.rs	0.00%	56 Missing ⚠️
src/uu/sed/src/delimited_parser.rs	0.00%	2 Missing ⚠️
src/uu/sed/src/sed.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #109   +/-   ##
=====================================
  Coverage   0.00%   0.00%           
=====================================
  Files         13      13           
  Lines       2664    2721   +57     
  Branches     225     231    +6     
=====================================
- Misses      2664    2721   +57     

Flag	Coverage Δ
macos_latest	0.00% <0.00%> (ø)
ubuntu_latest	0.00% <0.00%> (ø)
windows_latest	0.00% <0.00%> (ø)

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[sylvestre]

Looks great, thanks!