Remove GradleConnection APIThe GradleConnection API was our first attempt atimplementing composite builds. We have improved on thatin Gradle 3.1, allowing the user to define composite buildsin settings.gradle and giving the user much more controlover how dependency substitution works.A composite build is a normal Gradle build as far as theTooling API is concerned, so the separate concept ofthe GradleConnection is no longer needed. We will addmethods for fetching all models from a composite buildto ProjectConnection in Gradle 3.2
Specify which tests should NOT be run with an integrated compositeInstead of specifying the tests that DO work with an integrated composite,we specify which ones do not yet work. This should make it easier to identifythe tests that still need fixing. Before integrated composite can be consideredfully functional from the Tooling API, all of these tests need to be fixed.
Enabled testing of integrated composites for many casesFor tests that are already functional, we now test an 'integrated' compositewhen testing against the current (under-development) gradle version, retainingthe existing coverage with a non-integrated composite for older versions.Note that this isn't great, since we've removed coverage for a non-integratedcomposite against the current gradle version. Need to enhance the test runnerto include both scenarios.