[feat] Add UI for the Subflow task dispatcher

1. UI looks like a normal workflow node
2. Options for navigation to the selected flow:
a) do nothing, the user normally goes to sublow as a regular flow via the sidebar,
b) somewhere in the UI, node, or inthe details panel, there is a link to the sublflow and it opens
a) in the main workflow editor
b) as a pop-up
c) in a tab(workflow editor should support tabs in this case)