Restructure POM files for docker images and buildpacks to adopt inheritance for better code management

[Fluctuationqt]

From xsk created by alexkuklin: SAP/xsk#1644

Target

Change a way POM's are organized so changes to base components configuration could be made at one place, without need to copy-paste them to all POM files.

i.e., sap-cf and sap-kyma have almost no difference:

<   <name>XSK - Releng - Cloud Foundry</name>
<   <artifactId>xsk-releng-cf</artifactId>
---
>   <name>XSK - Releng - Kyma</name>
>   <artifactId>xsk-releng-kyma</artifactId>
97c97
<       <!-- Cloud Foundry - Base -->
---
>       <!-- Kyma - Base -->
100c100
<           <artifactId>dirigible-sap-cf-base</artifactId>
---
>           <artifactId>dirigible-sap-kyma-base</artifactId>

so it should be restrictured to sap version as parent and sap-cf and sap-kyma as subverstions of sap.

Other notes on the matter a placed in #1498 comments.

[Fluctuationqt]

Test the image on Kyma.