Replace Plugin-Local with Composite Build

[DanielJette]

What does this change accomplish?

Resolves #209

How have you achieved it?

• https://docs.gradle.org/current/samples/sample_composite_builds_plugin_development.html#buildscript_dependencies_are_substituted
• https://docs.gradle.org/current/userguide/composite_builds.html#:~:text=In%20a%20composite%20build%2C%20Gradle,project%20path%20of%20the%20project.

Scope of Impact and Testing instructions

The samples and libraries should be unaffected from this change. API should be consistent with 3.1.0, but the local builds will now use Composite Builds instead of requiring a local copy of the plugin jar.

I have tested and published an alpha version of this to 3.2.0-alpha05

Notice

Warning

This change must keep main in a shippable state; it may be shipped without further notice.

[DanielJette]

The issue I keep running into is that composite builds appear to require the java-gradle-plugin plugin. However, this plugin manipulates the published artifacts in undesirable ways that I have not figured out how to control. It seems to duplicate and replace some of, but not all of, the publishing configuration we have set in publish.build.gradle

The trick is to set automatedPublishing = false which will prevent the creation of a duplicate/unnecessary publishing block.

[jaredh]

Love seeing that JAR deleted finally. 😍

[jaredh]

Probably a sign that we should move to letting the plugin generate the publications itself, but glad this is all it took.

[DanielJette]

Absolutely not. Never touching publishing again unless something is deprecated or broken 😆
I spent an embarrassing amount of time trying to get the built-in publishing to produce a properly signed plugin that was compatible with Maven Central. gradlePlugin is designed to publish to https://plugins.gradle.org/ and the Maven Central support is confusing and seemingly impossible to configure properly.