Make template set root directories accessible for the reader

[jan-vcapgemini]

Currently we determine the folder for the template set utilities like this: https://github.com/devonfw/cobigen/blob/ac2efa9bf52a67f015d53d7a825b9cc0e9d5e399/cobigen/cobigen-core/src/main/java/com/devonfw/cobigen/impl/config/TemplateSetConfiguration.java#L187-L196

Adjust the TemplateSetConfigurationManager here: https://github.com/devonfw/cobigen/blob/ac2efa9bf52a67f015d53d7a825b9cc0e9d5e399/cobigen/cobigen-core/src/main/java/com/devonfw/cobigen/impl/config/reader/TemplateSetConfigurationManager.java#L75-L82 to get access to the root directory of each template-set.