fix(github): fix zerotime issues for GraphQL

[petkostas]

Summary

GitHub GraphQL returns zero time (&time.Time{}) for nullable fields, this leads to GORM not properly handling this cases.
This PR:

• Introduces a new core helper util NilIfZeroTime in order to ensure that *time.Time fields are assigned the nil value.
• Fixes the relevant cases in both collectors and extractors (as existing entries in the DB should be properly handled as well).

Does this close any open issues?

Closes #8538

Screenshots

⚠️ Screenshots pending, as this PR has not been tested yet.

⚠️ This PR has not been tested yet, I am looking for cases to properly test the fixes ⚠️

[klesh]

Hi @petkostas, I saw the review request this morning, but since the PR is still in draft, I wasn’t sure if it’s ready for review yet?

[petkostas]

Hey @klesh
I need to test this potentially with repo that re-produces the initial problem. I added you in case you wanted to do a first check regarding the approach.
But feel free to ignore until I have tested it and removed the draft.

[klesh]

Hey @klesh I need to test this potentially with repo that re-produces the initial problem. I added you in case you wanted to do a first check regarding the approach. But feel free to ignore until I have tested it and removed the draft.

I see — very thoughtful, thanks for the explanation!

I’d prefer to review after the tests are done, since in most cases the behavior depends more on the 3rd-party implementation (i.e., the actual response from GitHub GraphQL) than on our code, which is relatively straightforward.

In other words, field tests are more critical here than the code review 😂