add more type information to the 'webSocketHandler' method

[devoncarew]

• add more type information to the 'webSocketHandler' method; it now expects a typed closure instead of a Function
• see add type information to the webSocketHandler onConnection callback #457
  -rev to 3.0.0

We'll need to update several packages (test, dds, ...) before this can land and be published. We can do that thuswise:

• update the webSocketHandler calls to pass in a closure taking two params (see the changelog for an example)
• widen their dep. range to take both shelf_web_socket v2 and v3 (the change above will retain compatibility w/ v2, and will make it future proof for the anticipated v3 version)
• publish test, dds, ...
• land and publish this

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[devoncarew]

ping @brianquinlan (not sure if you saw this as it landed while you were OOO)