Improve the annotations-implementation

[FDelporte]

@Annotations is an area that needs to be improved in the code. A standards-based approach for dependency injection and handling Pi4J specific annotations needs to be investigated

• Java EE CDI?
  • https://www.baeldung.com/java-ee-cdi
• Jakarta EE CDI?
  • https://jakarta.ee/specifications/cdi/3.0/
  • https://jakarta.ee/specifications/cdi/3.0/cdi-spec-3.0.0-M4.pdf

Annotations are also a feature that could be removed from an initial release and added later.

These two examples show the idea of how the annotations could offer users internals of annotated syntax:

• https://github.com/Pi4J/pi4j-demo-telegraph/blob/master/src/main/java/com/pi4j/demo/telegraph/TelegraphUsingAnnotatedAI.java
• https://github.com/Pi4J/pi4j-demo-telegraph/blob/master/src/main/java/com/pi4j/demo/telegraph/TelegraphUsingAnnotatedDI.java

[FDelporte]

Further to be investigated:

• https://weld.cdi-spec.org/news/tags/tips/
• https://blog.creekorful.com/2019/08/using-cdi-2-0-in-a-java-se-application/

[FDelporte]

As agreed with @savageautomate the existing initial implementation has been stripped out of the master branch but is still available in https://github.com/Pi4J/pi4j-v2/tree/feature/%2322-annotations. To be decided later if and how we want to re-add this for a future version and/or if this should be a separate project.