Suggestions for the count content values transformation

[mephenor]

Mostly renamed some things and switched some stuff around.

The content prefix was a bit confusing, because it seemed like that should refer to entities in what's denoted by class_name, but that was already taken by the target prefix here...

• target prefix should be as before, but renamed everything that is pointed to by the relation path to have a referenced prefix.
• Factored the content of the outermost loop out into its own function and removed context class to reduce clutter a bit.
• Changed function signatures to require kwargs and only pass around, what's really required by creating a few intermediate variables. Should hopefully be easier on the eyes this way
• Renamed some functions and adjusted docstrings to be less generic

Hope that fits the intended purpose

[coveralls]

Pull Request Test Coverage Report for Build 11731960176

Details

• 33 of 36 (91.67%) changed or added relevant lines in 1 file are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.007%) to 93.124%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/metldata/builtin_transformations/count_content_values/data_transform.py	33	36	91.67%

Files with Coverage Reduction	New Missed Lines	%
src/metldata/builtin_transformations/count_content_values/data_transform.py	1	90.0%

Totals
Change from base Build 11722640716:	-0.007%
Covered Lines:	921
Relevant Lines:	989

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💛 - Coveralls

[sbilge]

In add_content_properties -> data_transform.py transformation, the same fn call is assigned to the variable name object which is not super explanatory. It would be good to change that too.

[sbilge]

But I can do it in the main PR.