Add a sed utility

[DavidHuber-NOAA]

Description
This creates a utility to build a sed search/replace command and pipe the output to another file.

Type of change

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

How Has This Been Tested?

• pynorms
• pytests

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes need updates to the documentation. I have made corresponding changes to the documentation
• My changes generate no new warnings
• New and existing tests pass with my changes

[codecov]

Codecov Report

Attention: Patch coverage is 88.88889% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 49.21%. Comparing base (63db259) to head (fb0c04d).

Files	Patch %	Lines
src/wxflow/file_utils.py	88.88%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop      #23      +/-   ##
===========================================
+ Coverage    47.99%   49.21%   +1.22%     
===========================================
  Files           18       18              
  Lines         1642     1660      +18     
  Branches       330      334       +4     
===========================================
+ Hits           788      817      +29     
+ Misses         798      787      -11     
  Partials        56       56              

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