feat: Manage -> Asset -> STIG Assignments replaced with available/assigned interface

[csmig]

The current interface for assigning a STIG to an individual Asset uses a pull-down that is hard to navigate for large numbers of STIGs. It is also the last bit of UI that uses this style.
Refactor the STIG Assignment interface for Assets to something similar to the Available/Assigned style interface implemented in the inverse assignment feature of assigning at Asset to a STIG in the STIGs panel.
Goals:
consistency and overall better experience

Changes to Manage Collection interface, Asset panel:
Create Asset pop-up
Modify Asset pop-up

• Replace current contents of STIG Assignments box in pop-up with
  • Available STIGs (All STIGs not assigned to the Asset) , rule count
  • left/right/drag element
  • Assigned STIGs (List of STIGs currently assigned to Asset), rule count
• STIG column should be filterable, rows should be checkboxes
• Maintain Save button action to update/create the asset

Further refinement TBD:
Pop-up may need to be enlarged/rearranged to make a little more room for the new interface