Verify that a Gradle release does not break any guides

We should treat the guides as downstream consumers of Gradle-the-build-tool and, as we do for other important downstream consumers such as plugins, make sure we don't release a Gradle version that doesn't work with a published version of a guide.

We should do this in the same way that we gate the release for other downstream consumers, by adding a stage to the build tool CI pipeline that tests the consumer against the candidate release (the distribution) and fails the pipeline on test failure (i.e. it gates the release on failure). This might happen as part of the 'master accept' stage or the 'release accept' stage.

Start by examining the build tool CI pipeline, especially the existing master accept and release accept stages that gate other downstream consumers such as plugins. Determine how a published guide is tested against the candidate distribution and add the guide consumer check there. Done means the pipeline fails when a guide test fails and prevents the release.

Written by the indexing model from the issue text.