Add VSCode Dark Modern and Light Modern color schemes (#19728)

This adds both the Dark Modern and Light Modern color schemes from
VSCode to match issue #19162.

I pulled the colors directly from VSCode's terminalColorRegistry.ts for
accuracy. The existing Dark+ scheme uses the older terminal colors from
before VSCode introduced the Modern variants, so this gives users access
to the newer palette.

The Dark Modern background is #1F1F1F which is the actual color used in
VSCode currently, not #1E1E1E from the legacy theme. Light Modern uses
#FFFFFF background with #3B3B3B foreground text.

Tested locally in Windows Terminal and both schemes render correctly.

src/cascadia/TerminalSettingsModel/defaults.json

@@ -350,6 +350,52 @@
             "brightCyan": "#29b8db",
             "brightWhite": "#e5e5e5"
         },
+        {
+            "name": "VSCode Dark Modern",
+            "foreground": "#CCCCCC",
+            "background": "#1F1F1F",
+            "cursorColor": "#FFFFFF",
+            "selectionBackground": "#264F78",
+            "black": "#000000",
+            "red": "#CD3131",
+            "green": "#0DBC79",
+            "yellow": "#E5E510",
+            "blue": "#2472C8",
+            "purple": "#BC3FBC",
+            "cyan": "#11A8CD",
+            "white": "#E5E5E5",
+            "brightBlack": "#666666",
+            "brightRed": "#F14C4C",
+            "brightGreen": "#23D18B",
+            "brightYellow": "#F5F543",
+            "brightBlue": "#3B8EEA",
+            "brightPurple": "#D670D6",
+            "brightCyan": "#29B8DB",
+            "brightWhite": "#E5E5E5"
+        },
+        {
+            "name": "VSCode Light Modern",
+            "foreground": "#3B3B3B",
+            "background": "#FFFFFF",
+            "cursorColor": "#000000",
+            "selectionBackground": "#ADD6FF",
+            "black": "#000000",
+            "red": "#CD3131",
+            "green": "#00BC00",
+            "yellow": "#949800",
+            "blue": "#0451A5",
+            "purple": "#BC05BC",
+            "cyan": "#0598BC",
+            "white": "#555555",
+            "brightBlack": "#666666",
+            "brightRed": "#CD3131",
+            "brightGreen": "#14CE14",
+            "brightYellow": "#B5BA00",
+            "brightBlue": "#0451A5",
+            "brightPurple": "#BC05BC",
+            "brightCyan": "#0598BC",
+            "brightWhite": "#A5A5A5"
+        },
         {
             "background": "#000000",
             "black": "#000000",