feat: add gitObjectHashLength option to keygen-git-hash-plugin

[YutaUra]

What does this change?

I added an option to reg-keygen-git-hash-plugin to change the length of the git object ID.

It is known that the default value of objectHashLength (also referred to as abbrev) is 7.
Additionally, the getBranchHash and getIntersection functions use an 8-character abbreviated commit hash.

According to a collision probability approximation based on the birthday problem,
an 8-character commit hash has about a 20% chance of collision when there are approximately 44,000 commits.
This is a realistic scenario in large-scale repositories.

References

• [reg-keygen-git-hash-plugin] Ambiguous short hash #597
  • This issue was considered resolved by using reg-simple-keygen-plugin, but that’s not a fundamental fix. Since I encountered the same problem myself, I’ve implemented a proper fix.

Screenshots

If applicable, add screenshots to help explain your changes.

What can I check for bug fixes?

Please take a look at the additional test cases. These cases demonstrate that setting objectHashLength to 3 causes a failure, while setting it to 10 works successfully. (Since it's difficult to create a case where the default value of objectHashLength —which is 7— fails, the test uses somewhat extreme values.)

[YutaUra]

Hi @Quramy,
I know you're very busy, but I’d be grateful if you could take a look when you get a chance. Appreciate your time!