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

res/terminal/Generate-TerminalAssets.ps1

@@ -24,6 +24,7 @@ Param(
   [string]$Path,
   [string]$Destination,
   [int[]]$Altforms = (16, 20, 24, 30, 32, 36, 40, 48, 60, 64, 72, 80, 96, 256),
+  [int[]]$Win32IconSizes = (16, 20, 24, 32, 48, 64, 256),
   [switch]$Unplated = $true,
   [float[]]$Scales = (1.0, 1.25, 1.5, 2.0, 4.0),
   [string]$HighContrastPath = "",
@@ -115,6 +116,7 @@ If (-Not [string]::IsNullOrEmpty($Destination)) {
   $TranslatedOutDir = "."
 }
 
+$intermediates = [System.Collections.Concurrent.ConcurrentBag[PSCustomObject]]::new()
 $intermediateFiles = [System.Collections.Concurrent.ConcurrentBag[string]]::new()
 
 # Generate the base icons
@@ -136,6 +138,11 @@ $allSizes | ForEach-Object -Parallel {
   }
 
   ($using:intermediateFiles).Add($intermediateStandardNt)
+  ($using:intermediates).Add([PSCustomObject]@{
+      Contrast = "standard"
+      Size = $sz
+      PathWSL = $intermediateStandardWsl
+  })
 
   If ($svgContrastWsl -Ne $null) {
     $intermediateBlackNt = "$destinationNt\_intermediate.black.$($sz).png"
@@ -158,9 +165,28 @@ $allSizes | ForEach-Object -Parallel {
 
     ($using:intermediateFiles).Add($intermediateBlackNt)
     ($using:intermediateFiles).Add($intermediateWhiteNt)
+    ($using:intermediates).Add([PSCustomObject]@{
+        Contrast = "black"
+        Size = $sz
+        PathWSL = $intermediateBlackWsl
+    })
+    ($using:intermediates).Add([PSCustomObject]@{
+        Contrast = "white"
+        Size = $sz
+        PathWSL = $intermediateWhiteWsl
+    })
   }
 }
 
+$intermediates | ? { $_.Size -In $Win32IconSizes } | Group-Object Contrast | ForEach-Object -Parallel {
+  $assetName = "terminal.ico"
+  If ($_.Name -Ne "standard") {
+    $assetName = "terminal_contrast-$($_.Name).ico"
+  }
+  Write-Host "Producing win32 .ico for contrast=$($_.Name) as $assetName"
+  wsl convert $_.Group.PathWSL "$($using:TranslatedOutDir)/$assetName"
+}
+
 # Once the base icons are done, splat them into the middles of larger canvases.
 $allAssetSizes | ForEach-Object -Parallel {
   $asset = $_