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

• [x] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [x] This change requires a documentation update

How Has This Been Tested?

• [x] pynorms
• [x] pytests

Checklist

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

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 :warning:
src/wxflow/yaml_file.py	0.00%	1 Missing and 1 partial :warning:
src/wxflow/jinja.py	0.00%	0 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ 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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