Chore: unit tests

[willshowell]

• [x] passing invalid popover throws error
• [x] SatPopoverAnchor#open/close/toggle
• [x] SatPopover#open/close/toggle
• [ ] positioning + classes
• [ ] changes in position while open
• [x] backdrop clicks
• [x] escape keydown
• [x] focus trap

[willshowell]

SatPopover

• Inputs
  • xPosition
  • yPosition
  • overlapAnchor
  • ~hasBackdrop~
  • ~backdropClass~
• Output
  • ~opened~
  • ~closed~
• Methods
  • ~open~
  • ~close~
  • ~toggle~

SatPopoverAnchor

• Inputs
  • ~satPopoverAnchorFor~
• Outputs
  • ~popoverOpened~
  • ~popoverClosed~
• Methods
  • ~popoverOpen --> Needs rename to isOpen~
  • ~togglePopover~
  • ~openPopover~
  • ~closePopover~
  • ~destroyPopover~ --> Would there be any wisdom to making this private? (edit: yes, done, can be made public later if needed)