feat(validation-tests): validation tests path resolution

[meganwolf0]

Description

Updates the validation testing and fixes a bug with the way indicies were identified (see #840 ) for specific bug.
This PR includes

• Re-factor of the existing filter/path functionality. Intent was to increase test coverage and generally make this package easier to understand/use
• Additional functionality to delete an item from a list (this was not previously supported). Solving the bug above yielded some code that made this functionality pretty easy to implement.
• Updated the path parsing to make it more semantic for users - previously all items needed to be "." delimited, now made it so key[foo=bar] is equivalent to key.[foo=bar]
• DOCS! Added some new docs for testing a validation, as I felt that was missing context. Also updated the testing.md reference doc.

Related Issue

Fixes #840

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Other (security config, docs update, etc)

Checklist before merging

• Test, docs, adr added or updated as needed
• (N/A)Schema Updates applied
• Contributor Guide Steps followed

[mildwonkey]

One typo to fix, the other suggestions you are free to take or ignore as you see fit! This looks good, and I like your documentation.

[mildwonkey]

LGTM 👍🏻

(I'll re-approve if you want to change the integer map key wording but my actual requested changes are resolved)

[mildwonkey]

I like the changes! 😀 ❤️

[brandtkeller]

I really like the test-a-validation.md doc.