fix(generator): support nil returns when using interface typed params

[jfragosoperez]

Description

• Types using generic typed interface params, should allow nil values on return.

• Some test/example mocks haven't been regenerated recently, so 'task mock' removed and recreated mocks taking into account the yaml config and package movements, etc.

• Fixes Bug: Cannot return nil for generic type T, when T is an interface  #513

Type of change

• Bug fix (non-breaking change which fixes an issue)

Version of Go used when building/testing:

• 1.22
• 1.23

How Has This Been Tested?

• Added test coverage
• Regenerate test mocks to reflect the changes (NOTE: interface{} renamed to any by default for new golang versions)

task mocks
task test

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

[LandonTClipp]

Thank you for the PR, this is on my radar so I will give it a review once I find some spare time... hopefully very soon 👍🏻

[jfragosoperez]

@LandonTClipp cool, I'll wait for your news, in case any changes were required, I'll apply them ASAP. Thanks

[LandonTClipp]

Ah, a simple fix! Thank you. One comment about the test.

[LandonTClipp]

Wonderful, thank you!

[jfragosoperez]

@LandonTClipp I rebased and squashed into a single commit, so you're able to merge (the workflow will need to run first though)