tests(v3): add tests for template funcs

[ravsii]

Description

Added tests for template functions, did some refactor of existing ones as well.

• Fixes v3: Extend tests for template funcs to include shared funcs #916

Version of Go used when building/testing:

• 1.22
• 1.23

How Has This Been Tested?

Added tests

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[ravsii]

couldn't find a better type that implements that interface, and I can't change the underlying type of a slice element, so it's []<nil> in the tests

[ravsii]

Also, I think it's time to add 1.24 to the pipeline

[LandonTClipp]

Awesome this is great! Thanks. I will take a closer look later.