configuration cache: exposeAsEnvironment/SystemProperties()

[mikewacker]

Fixes #452

Usage Notes

With the configuration cache enabled, users will also need to capture dockerCompose in a local variable. Example (Kotlin):

tasks.named<Test>("test") {
    val dockerCompose = dockerCompose
    doFirst {
        dockerCompose.exposeAsEnvironment(this@named)
    }
}

Without the val dockerCompose = dockerCompose line, you would get an error like this:

1 problem was found storing the configuration cache.
- Task `:lib:test` of type `org.gradle.api.tasks.testing.Test`: cannot serialize Gradle script object references as these are not supported with the configuration cache.
  See https://docs.gradle.org/9.1.0/userguide/configuration_cache_requirements.html#config_cache:requirements:disallowed_types

Notes

The code comments have an important corollary for the tests.

• Calling a task action directly (i.e., f.project.tasks.composeUp.up()) does not complete the task.
• Corollary: Tests always call composeSettings.servicesInfos before the composeUp task is "completed."

Additional Testing

Uses example.zip, which calls exposeAsSystemProperties() directly.

1. ./gradlew publishToMavenLocal (for the plugin)
2. ./gradlew clean build (for the example)