Feat/524/interface consistency

[willmeister]

Description

Makes interfaces consistent. Use descriptive implementation name where possible. If meant to be a single-implementation interface or there is no easy descriptive name, class SomeName implements SomeNameInterface.

Metadata

Fixes

• Fixes Set interface & other standards around pigi codebase #524

Contributing Agreement

• I have read and understood the Plasma Group Contributing Guide and Code of Conduct and am following those guidelines in this pull request.

[karlfloersch]

I'm not a big fan of the Interface suffix and would prefer using Default[ClassName] & keeping the Interface name as the abstract concept. I think Default is probably more descriptive than Base which is what we were using before.

That being said, I'm also a fan of not using interfaces for single implementations. There are long discussions about the pros and cons of this here which boil down to making mocking for tests easier if you have an interface for literally everything.

My preference when writing code is keeping as much fluff out as possible and I think that using Hungarian notation adds a bit of fluff & can promote busy-work style coding. There's a snippet from an article about interface naming which I like:

Think About Your Design!
You will probably encounter three different situations:

1. Your current code needs multiple implementations of a same concept.
2. Your current code provides one implementation of a concept, but is meant to be extended by more specialized third-party code.
3. Your current code only needs a single implementation, and there’s currently no point in extending it.

It then goes over different ways to handle the interface for each scenario. #3 is obviously the hardest where you end up wanting to call your interface the same thing as your implementation. In these cases Default or Impl or Base, or even not writing an interface all are reasonable options. This way we're only adding a non-descriptive prefix/suffix some of the time as opposed to adding extra syntax all the time.

All of this said, I also don't like bike shedding naming. So even if we were to use the Interface suffix it's certainly not the end of the world.

[karlfloersch]

This should be Key not KeyInterface I believe