Proposal: reorganize integration tests

[ghost]

I'm not a fan of the current state of integration testing. Right now, it is spread across two repositories, LGNBuilder and LGNC-Swift (will be even more as more languages become supported), which are too tightly and mutually dependent on each other, and making changes requires coordinated updating of both repositories.

I suggest to strip integration tests from both repositories and to place them in a designated one, let's say, LGNC-integration-tests. This repository shall contain both test schema and test contract implementations for each language. A script shall be written, which will pull as dependencies LGNBuilder and each LGNC-<lang> implementation, generate necessary code and run tests.

The advantages of this approach that I see are:

• Tests will become easier to comprehend, update and expand
• With some effort, test contract implementations may become examples of how to write contracts for each language, easily accessible for a newcomer
• Less chance for inadvertent coupling between a language implementation and its tests, since the implementation will be pulled as a dependency, like in a real world project
• A single point for observing all language implementations' compliance

Another suggestion, of which I am not certain, would be to put the builder, the tests and the general documentation into LGNC repository, to avoid spreading the project across too many repos.

Thoughts?