Documentation of AEM Application Format

Some documentation on the module structure format of "aemapp" packaging which can be processed with `package-app` mojo (https://github.com/adobe/aemanalyser-maven-plugin/blob/main/aemanalyser-maven-plugin/src/main/java/com/adobe/aem/analyser/mojos/PackageAppMojo.java) would be really helpful. Particularly interesting are answers for the following questions:

1. Is the mojo only necessary to deploy to the AEM SDK locally (in order to allow deployments via the package manager ReST API) or initially also required for Cloud deployments?
2. Is the `package-app` mojo only a temporary solution and direct deployment of those "jar" packagings are supported by some OSGi installer factory or some other means natively in the future?
3. Can a sample Maven module outlining the features of the AEM application JAR be provided?
4. Are nested AEM application Jars supported (similar to nesting FileVault Container Content Packages)?
5. Which Maven plugin supports packaging `aemapp`?

Start with PackageAppMojo.java and trace how the package-app mojo handles the aemapp format. Document whether it is needed for local SDK and Cloud deployments, its future status, nested JAR support, and which Maven plugin packages aemapp. Provide the requested sample Maven module describing an AEM application JAR.

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