Improve the visibility of the options to select

[marionbarker]

This PR is proposed as a solution to Loop Issue 2238: Make Checkmark List Items easier to see

Sample screen views using for this PR.

[dnzxy]

May I suggest to either

• conditionally (for dark mode only) adjust the color of the control, i.e., a lighter gray, or extending the line width, or
• opting to use white or black color, depending on theme, so .primary.

The blue color (.accentColor) is associated with something active / selected.

[marionbarker]

In the Issue, @ps2 requested "stick to existing iOS conventions for color".

I was not quite sure how to do that:

• Increasing lineWidth without making color modifications was not sufficient
• Replacing Color.accent with Color.primary gave good contrast but was more black and white than @ps2 example graphics
• I adjusted the .foregroundColor from systemGray4 to systemGray2 to systemGray
  • I thought that looked better, but I could hear @itsmojo asking me to consider his "aging & colorblind eyes"
  • So I also increased lineWidth to 2

I captured a bunch of other screen shots, but I think these are sufficient.

Original and current commit Dark

Original and current commit Light

[itsmojo]

I'm not qualified to say anything on color schemes, but the current commit Dark and Light views do look good to my eyes...

[ps2]

Yes, I think the line width increase makes it a lot more visible, and the color matches the conventions we see in iOS. Thanks!