Change Pen Icon to Edit Button

CW (11/7/2019): The 'pen' icon is displayed in several FOLIO apps, e.g. Users, eHoldings and other apps. So we'll leave this suggested UX change for now, and instead wait for the new "Edit button combined with action menu" which will replace the top menu caret with action menu.

Purpose: UX wants us to change the pen icon to edit buttons.

Scenarios:

1. Scenario
   • Given an instance record
   • When displaying in view mode to a user with edit permissions
   • Then the pen icon should be replaced with an edit button
2. Scenario
   • Given a holding record
   • When displaying in view mode to a user with edit permissions
   • Then the pen icon should be replaced with an edit button
3. Scenario
   • Given an item record
   • When displaying in view mode to a user with edit permissions
   • Then the pen icon should be replaced with an edit button

See this doc for the origin of this requirement from UX: https://docs.google.com/document/d/1D6tuooigz3DMJkFrxzjE-rII7yYRFpvYuPEbO10_ivA/edit

NOTE: This story was split off from UIIN-530