Environment

Windows build number: 10.0.18363.0
Windows Terminal version: 1.4.3243.0

Steps to reproduce

1. Update settings.json to use the One Half Light, Solarized Light, or Tango Light color schemes.
2. Use the mouse to highlight some text.

Expected behavior

It's easy to see which text was selected.

Actual behavior

It's hard to see which text was selected because the default selectionBackground value is white, and that doesn't work well with light color schemes.

Proposed solution

Add selectionBackground values to all of the color schemes in defaults.json (or at least the light color schemes).

Related to

This issue is related to #3326, #3561, and #3580.