Fix the bad default light theme selection background color (#16789)

## Summary of the Pull Request
Fixed default selection background colors with light schemes. Default
color now matches the scheme and contrasts well
## References and Relevant Issues
none
## Detailed Description of the Pull Request / Additional comments
This is my first contribution ever :) Even though its simple, im happy
to help
## Validation Steps Performed

## PR Checklist
- [ ] Closes #8716 
- [ ] Tests added/passed
- [ ] Documentation updated
- If checked, please file a pull request on [our docs
repo](https://github.com/MicrosoftDocs/terminal) and link it here: #xxx
- [ ] Schema updated (if necessary)

src/cascadia/TerminalSettingsModel/defaults.json

@@ -174,7 +174,7 @@
             "foreground": "#383A42",
             "background": "#FAFAFA",
             "cursorColor": "#4F525D",
-            "selectionBackground": "#4F525D",
+            "selectionBackground": "#383A42",
             "black": "#383A42",
             "red": "#E45649",
             "green": "#50A14F",
@@ -219,7 +219,7 @@
             "foreground": "#657B83",
             "background": "#FDF6E3",
             "cursorColor": "#002B36",
-            "selectionBackground": "#073642",
+            "selectionBackground": "#2C4D57",
             "black": "#002B36",
             "red": "#DC322F",
             "green": "#859900",
@@ -264,7 +264,7 @@
             "foreground": "#555753",
             "background": "#FFFFFF",
             "cursorColor": "#000000",
-            "selectionBackground": "#555753",
+            "selectionBackground": "#141414",
             "black": "#000000",
             "red": "#CC0000",
             "green": "#4E9A06",