Interim solution for handling DTL and BPL files

[gjsjohnmurray]

When working server-side using isfs we can already list .bpl and .dtl items as long as the folder uri specifies a filter queryparam that allows them through. For example "uri": "isfs://dem-dev/?ns=ENSDEMO&filter=*"

But when a BPL is the opened from Explorer the document contains a single line:

/csp/ensdemo/EnsPortal.BPLEditor.zen?BP=Demo.Workflow.HelpDesk.BPL&STUDIO=1

An example of a DTL is:

/csp/ensdemo/EnsPortal.DTLEditor.zen?DT=Demo.ComplexMap.Transform.CreateClassBatch.DTL&STUDIO=1

Ultimately (see #60) it'd be nice to have the GUI editors open withing VS Code. But until this happens a possible workaround would be to turn the above into clickable links that launch an external browser page.