Add new features for archiving

[DavidHuber-NOAA]

Description

This adds a new jinja filter to get the relative directory of a path given a root path and a symlink dereference option to htar create methods. It also gives a better use case example for the Executable class and a check for the existence of a template file before attempting to parse it (not doing so causes a downstream failure that is difficult to debug).

Needed for NOAA-EMC/global-workflow#2345.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• 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
• Any dependent changes have been merged and published

[DavidHuber-NOAA]

A note on the new dereference flag: I wrote and used this in archiving, but then later did not need it. I decided to keep it as it seems useful for having compatibility with Python's builtin tarfile methods.

[codecov]

Codecov Report

Attention: Patch coverage is 25.00000% with 6 lines in your changes are missing coverage. Please review.

Project coverage is 47.90%. Comparing base (63db259) to head (534fe44).

Files	Patch %	Lines
src/wxflow/htar.py	40.00%	3 Missing ⚠️
src/wxflow/yaml_file.py	0.00%	1 Missing and 1 partial ⚠️
src/wxflow/jinja.py	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop      #24      +/-   ##
===========================================
- Coverage    47.99%   47.90%   -0.09%     
===========================================
  Files           18       18              
  Lines         1642     1647       +5     
  Branches       330      333       +3     
===========================================
+ Hits           788      789       +1     
- Misses         798      801       +3     
- Partials        56       57       +1     

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[aerorahul]

Looks good.