Support modules without 'main' source set

[jjohannes]

Description

The use case is to only have testFixtures (and multiple test sets) in a module.

Currently, you need to add this, as Gradle is adding the dependency between testFixtures and main by default.

configurations {
    testFixturesApi {
        withDependencies { this.removeIf { it is ProjectDependency && it.name == project.name } }
    }
}

Otherwise you get an error like this:

      > Execution failed for ExtraJavaModuleInfoTransform: ./module-0.68.0-SNAPSHOT.jar.
         > Not a module and no mapping defined: module-0.68.0-SNAPSHOT.jar

Steps to reproduce

Create a module that does not contain a src/main/java folder.

Additional context

No response

Hedera network

No response

Version

0.6.0

Operating system

macOS

[jjohannes]

Fixed by #343