Gate: Persist Business Partner Output

[nicoprow]

Currently the Gate stores the business partner input, that is the business partner information how the sharing member shares it. The Gate should also store the clean and processed business partner information which is the result from the sharing process, we call this the business partner output.

For this, the Gate should get a new PUT endpoint for each LSA type to set the output for business partners. Here, business partners should be identified by external id. Upon receiving the output content for a business partner the Gate should persist it in the database. For each business partner there should only be one input and maximal one output content at the same time.