Enable searching for included templates when rendering jinja2 templates.

[aerorahul]

Description
The current implementation of jinja2 rendering was unable to support include when the included template was in a location not directly under the current template directory.
This PR:

• allows jinja to search for templates in paths that are provided as searchpath as well as from /
• removes the parsing of mixed jinja and other template form $( ) from function parse_j2yaml. This was a stop gap measure to allow prototyping in the DA applications. Those have now matured that this stop gap needed to be addressed holistically.
• contains some minor code cleanup where appropriate in jinja2.py and yaml_file.py. Test for the include is added.
• updates github actions versions for checkout, setup-python. Also updates the authentication to code-cov v4 that requires use of token stored as a secret.

Type of change

• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

• pynorms
• pytests
• in a downstream DA application with robust use of include including nesting.

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

[codecov]

Codecov Report

Attention: Patch coverage is 84.21053% with 6 lines in your changes are missing coverage. Please review.

Project coverage is 48.87%. Comparing base (d69dbbc) to head (968cddd).

Files	Patch %	Lines
src/wxflow/jinja.py	86.20%	3 Missing and 1 partial ⚠️
src/wxflow/schema.py	0.00%	1 Missing ⚠️
src/wxflow/yaml_file.py	87.50%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop      #15      +/-   ##
===========================================
- Coverage    48.91%   48.87%   -0.05%     
===========================================
  Files           15       15              
  Lines         1429     1416      -13     
  Branches       305      308       +3     
===========================================
- Hits           699      692       -7     
+ Misses         676      670       -6     
  Partials        54       54              

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