Workflow Types; add Mermaid Flowchart

Workflow Types can now display a Mermaid Flowchart of the Workflow Type's Items.

Under the Tools group in the Actions pane, click "Mermaid Flowchart" to open a browser window displaying a Flowchart based upon the items defined for the Workflow Type.

Note, if the Workflow Type has script code, this may affect the flow.

This uses the Flowchart markdown syntax as defined at https://mermaid.live/ and relies on the render provided by Mermaid.