[Feat] Visualizer Config

[philipp-seitz]

Currently, we use the same configuration for visualizing all workflows and open ones, so we cant have them open at the same time.
We could improve this by:

• having a link in the regular one to point to the wfs under construction
  • need to think through how to keep track of them, e.g. a file we watch on
• a config file we ship from the backend (which can be provided by the user)
  • e.g. custom color schemes
  • other configs