Split VCS Provider into several smaller provider interfaces

[AdmiringWorm]

Detailed Description

Currently we are using a single monolithic interface that all supported providers need to support, we should split out this interface into smaller more related interfaces that can be used to implement specific sections of a provider when needed.

Context

To be able to only support certain aspects of a provider, without having to reimplement the entire VCS provider interface.

Possible Implementation

N/A

Your Environment

• Version Used: 0.18.0
• Edition Used (.NET Core, .NET Framework): .NET Core
• Operating System and version (Windows 10, Ubuntu 18.04): Windows