Refactored FrameworkCompatibilityService for use in NuGet.Jobs

[advay26]

We want to reuse the FrameworkCompatibilityService in the NuGet.Jobs repo to get packages' computed frameworks in the Search index-builder jobs. To make this code easier to reuse, I made it a static class. I also updated all its existing references and tests.

Part of https://github.com/NuGet/Engineering/issues/4979

[erdembayar]

To make this code easier to reuse

Can you please explain this part? How exactly does it make it easier? Isn't using as it's almost the same as this, except for some dependency injection and constructor parameters?

[joelverhagen]

Seems fine to me. If we get to a point where we need to pass feature flags, configuration, or other services in as static method parameters, then we'll know it should move back to being a non-static service acquired via DI.

[advay26]

To make this code easier to reuse

Can you please explain this part? How exactly does it make it easier? Isn't using as it's almost the same as this, except for some dependency injection and constructor parameters?

@erdembayar You're probably right that we could do it that way too. I don't have much context on how to add dependency injection here, so that was part of my motivation for doing it this way.

However, I also didn't see any reason why this service couldn't just be static. All its other members were already static, and this class doesn't need to store any state.