Tenant option injection into docker environment

Currently we inject tenant options with the same category as the microservice name into each incoming request. First of all there is a risk of creating huge (maybe too huge) HTTP headers.

In a technical workshop with ADAMOS, ASM and elunic we discussed that it would be very nice if you can configure through the manifest which tenant options are injected. The idea would also be to have them accessible as environment variables all the time instead of only injecting them into the request.