Add Micrometer [bff]

Add Micrometer [bff]

- add Micrometer dependencies
- uses Zipkin as trace protocol, typically for port 9411
- requires changing dependency injection of WebClient.Builder [1]

[1] Micrometer is injecting the trace context into the WebClient.Builder bean.
To add the ExchangeFilterFunctions for authentication, errorhandling and logging, the existing bean needs to be modified instead of statically creating a new one

Issue-ID: PORTALNG-57
Change-Id: I13dd18d297cd56fa2dfbb525723c79f4abb41f87
Signed-off-by: Fiete Ostkamp <Fiete.Ostkamp@telekom.de>