Option to specify external configuration in a principled way

[vjovanov]

We need to provide a way to specify externally the reachability configuration for the dependencies of the project. The format of the external configuration folder is TBD
but it will follow a convention that allows mapping from a dependency's artifact ID to the config files.

The first proposal for the DSL entry:

graalvmNative {
    metadataRepository {
        enabled = true // default false until official repo release, true and optional later
        // path and version are mutually exclusive
        version = "0.0.1" // this would be the only mandatory field
        path = "/home/usr/dev/conf-repo|http://my.repo/|http://my.repo/repo-1.1.1.zip" // custom location or a local folder for development. default: empty which redirects to the configuration repo.
        ignoreDependencies = ["com.google.guava:guava"] // dependencies for which the repo is ignored. The version is omitted. 
    }
    binaries {
        main { 
        }
    }
}

In the first version, the configuration would be provided locally. Later we can use the GitHub releases, repository clones, or any other future mechanism.

[melix]

Fixed by #204 for Gradle. The name of the configuration block is currently jvmReachabilityMetadataRepository, which is a bit mouthful but accurate. We can shorten this to metadataRepository if needed.

graalvmNative {
    jvmReachabilityMetadataRepository {
        enabled = true // default false until official repo release, true and optional later
        // path and version are mutually exclusive
        version = "0.0.1" // this would be the only mandatory field
        path = "/home/usr/dev/conf-repo|http://my.repo/|http://my.repo/repo-1.1.1.zip" // custom location or a local folder for development. default: empty which redirects to the configuration repo.
        ignoreDependencies = ["com.google.guava:guava"] // dependencies for which the repo is ignored. The version is omitted. 
    }
    binaries {
        main { 
        }
    }
}

[sdeleuze]

+1 for using metadataRepository, in the context of being nested inside graalvmNative and properly documented that seems good enough to me.

[lazar-mitrovic]

Fixed by #204, #240 and #247.