Create example for using picocli JPMS modules

[remkop]

Create examples for modular usage.

Related to:

• [Make picocli-codegen an explicitly declared named JPMS module #1599] API: The picocli-codegen artifact is now an explicitly declared named JPMS module with a module-info.class.
• [Make picocli-groovy an explicitly declared named JPMS module #1611] API: The picocli-groovy artifact is now an explicitly declared named JPMS module with a module-info.class.
• [Make picocli-shell-jline2 an explicitly declared named JPMS module #1610] API: The picocli-shell-jline2 is now an explicitly declared named JPMS module with a module-info.class.
• [Make picocli-shell-jline3 an explicitly declared named JPMS module #1609] API: The picocli-shell-jline3 is now an explicitly declared named JPMS module with a module-info.class.
• [Make picocli-spring-boot-starter an explicitly declared named JPMS module #1608] API: The picocli-spring-boot-starter is now an explicitly declared named JPMS module with a module-info.class.

[remkop]

See https://stackoverflow.com/questions/69688720/using-picocli-with-picocli-shell-jline3-and-configured-java-modules-leads-to-unn

[remkop]

done: https://github.com/remkop/picocli/tree/main/picocli-tests-jpms-modules