Update styling of table row/column selector of Content Editor

Proposal

Update the styling of the active table row/column selector.

• Cell sizing
  • 16x16 px cells
  • 8px between cells
  • 8px padding between cells and popup container
• "Selected" cell
  • Fill color: $blue-50
  • Border color: $blue-500
  • Border: 2px
• "Idle" cell
  • Fill color: $white
  • Border color: $gray-200
• Try to avoid the extra space to the right in the popover

Content editor (!63945 (merged))	header

Changelog

• 20210813 - Update styling of squares (Figma)