Use annotations to declare potential analyzer contexts

Follow-up to #2754253: Lack of standard result in collaboration of analyzers

Problem/Motivation

#2754253: Lack of standard result in collaboration of analyzers is going to support contexts as a part of analyzers. They are currently created in-code when needed.

Proposed resolution

Declaring potential analyzer contexts through plugin annotations would help us to build a UI and be a first step with Rules integration.