1595 extend uprader to upgrade from monolithic structure to template set.xml

[quantumfate]

Adresses/Fixes #1595 .

Implements

• merge from context.xml and template.xml
• context.xml will be deleted and adapted to new template-set.xml

@devonfw/cobigen

[Lur1an]

The current implementation (on this branch) extends the upgrade function from V2.1 to V3 and directly generates a template-set.xml (V6) and skips the new context.xml generation. In doing so it breaks a lot of core code that expects new context.xml files from the upgrade.

I suggest to integrate this upgrader by skipping the V3 upgrade altogether and go directly from V2.1 Monolithic context.xml to template-sets.xml V6. This will require reworking the AbstractConfigurationUpgrader and related classes/methods.

Hint:

• check failing tests in core to see where to start reworking.

@jan-vcapgemini