Store workfiles information in the db

[iLLiCiTiT]

Changes

• added workfiles tool to pype.tools
• workfiles tool was updated with 2.x develop features (extensions combobox)
• workfiles document is stored to mongo db on workfiles creation
  • Document:

  {
      "type": "workfile",
      "filename": "<workfile filename>",
      "parent": <asset id>,
      "task_name": <task name>,
      "files": [<rootless workfile path>],
      "schema": "pype:workfile-1.0",
      "data": {...}
  }
  

• currently is workfile tool modification used only in maya and nuke because all other hosts can't easily change menu items
• it is possible to store artist note which is stored to data.note key in the document

Screenshot

[mkolar]

Works as expected. We'll need to clean up the GUI a bit, but I'm happy to leave that for another PR. have to think about it a bit more first.