Show processes

[bonndan]

As a user I want to see my processes and how they are affected by landscape states. Relates to #98

Instead of detailed items and relations processes (smaller directed subgraphs within the landscape) as a whole may be more interesting. Process should be the counterpart to groups: a collection of relations, with tags, labels, links etc.

Acceptance criteria:

• processes work like groups for items (linked, labeled etc): a collection of relations.
• support "queries" to biuld the collections
• the relations are ordered. Process can have many starting points and endpoint, but must not have gaps
• show colored processes on the map (introduce new model maybe consiting of a list of dataflow relation with a specific tag)
• allow to configure a process input dto in yaml by naming the items (similar to relation descriptions)
• export processes in the HTTP API
• processes can be assessed (as children of landscape, but without own children)