Improve contrast/visibility of focal point indicator

[rungta]

Description

The focal point indicator that is overlaid on the image and can be dragged around can sometimes be hard to spot depending on the visual contents of the image being edited, and the size of the browser window. E.g.:

Increased contrast for this bit of UI would help in quickly spotting:
a) The fact that the focal point indicator is enabled and somewhere on the image, and
b) The current focal point.

Additional info

• Craft version: 3.1.28

[jamiewade]

I have used a technique similar to this and has worked well in the past: http://www.kennethcachia.com/background-check/

[brandonkelly]

Ooh that’s pretty cool @jamiewade!