Update WT's icon at runtime to match high-contrast as applicable (#7971)

This commit introduces 8 more variants of the .ICO file, embeds the
right ones into WindowsTerminal.exe, and adds code that will select the
most appropriate icon at runtime.

Since we're a Centennial application, the "application" icon inside our
package isn't used by the shell for the taskbar thumbnails or the
Alt-Tab window.

To quote J. Tippet,
> I believe there are two possible fixes:
>
> 1. Fix the OS shell to prefer the MRT icon instead of preferring the
>    win32 icon
> 2. Add alternate versions of /res/terminal.ico
> The 1st fix is clearly better, since it benefits any hybrid app. But
> the 2nd fix is much easier, since it'd just take about an hour to gin up
> a new .ico file and hack the .RC file to refer to it when building the
> preview flavor.

... and to quote Michael Ratanapintha,

> Basically, if your MSIX-packaged desktop app's image resources are
> separate files or even separate MSIX packages, they may be loaded by
> MRT. If they're embedded in the .exe, they're the old-fashioned Win32
> resources Mr. Tippet is referring to.

This is the "2nd fix."

Fixes #6777

Co-authored-by: Jeffrey Tippet <jtippet@ntdev.microsoft.com>

.github/actions/spell-check/dictionary/apis.txt

@@ -3,14 +3,20 @@ ACCESSDENIED
 alignof
 bitfield
 bitfields
-COLORPROPERTY
 CLASSNOTAVAILABLE
+COLORPROPERTY
+CXICON
+CYICON
 environstrings
 EXPCMDFLAGS
 EXPCMDSTATE
 fullkbd
 futex
+GETDESKWALLPAPER
+GETHIGHCONTRAST
 Hashtable
+HIGHCONTRASTON
+HIGHCONTRASTW
 href
 IAsync
 IBind
@@ -25,8 +31,8 @@ IInheritable
 IMap
 IObject
 IStorage
-llabs
 LCID
+llabs
 lround
 LSHIFT
 NCHITTEST
@@ -46,14 +52,14 @@ RSHIFT
 rx
 serializer
 SIZENS
-GETDESKWALLPAPER
-UPDATEINIFILE
 spsc
 STDCPP
 strchr
 syscall
+THEMECHANGED
 tmp
 tx
+UPDATEINIFILE
 userenv
 wcstoui
 XDocument