frontend: editor: make configuration windows and mechanisms consistent

[ES-Alexander]

Current behaviour

• cog buttons in the "Widgets in View" list for regular and mini-widgets
  • Custom Widget Base opens a freestanding window without affecting the rest of the interface (so several can be stacked)
    • this has a closure X, which other popups don't
    • this can also be opened via the three dots in the top right corner of the widget itself
    • it also supports being renamed by double-clicking the name on the widget itself, including outside edit mode
  • other widgets open a popup that disables the whole rest of the interface
  • everything in the list has a cog button, even if it can't be configured
  • not everything is in the list that should be
• sidebar for Input widgets, with completely different styling
  • opens on click of the widget itself, on top of the View area

Expected or desired behaviour

1. Widget configuration does not have to be exclusive of movement --> the configuration options should ideally appear somewhere minimally disruptive to the rest of the editing process
   • The best place for this (in my mind) is the bottom bar, because while configuring one widget you are definitely not dragging another one into existence
2. The style and mechanisms need to be consistent, to avoid people having to learn several different interfaces to do effectively the same thing in slightly different contexts
   • Having configuration always occur in the bottom bar would help with this
     • This would also allow highlighting the currently "focused" widget both in the View and in the "Widgets in View" list in the sidebar
   • Making a widget the focus for configuration should only occur by:
     1. clicking it in the View,
     2. clicking its cog in the "Widgets in View" list in the left sidebar, or
     3. (advanced implementation) holding a designated modifier button and clicking the widget while outside of Edit Mode, as a shortcut to open Edit Mode with that widget in focus
   • Removing configuration focus should be possible by:
     1. clicking an X in the top right corner of the bottom bar
     2. clicking on an unused part of the View
     3. clicking on another widget, to swap the focus to it
   • Loading, saving, and renaming the Custom Widget base should be done exclusively via the configuration window

Prerequisites

• I have checked to make sure that a similar request has not already been filed or fixed.