Add Windows ARM build (#3112)

Unimplemented:

- ARM-native installer/uninstaller

Untested:

- Installer/uninstaller/updater
- Word integration DLL

Also updates the launcher and updater to 115.9.0esr for x64. win32 stays
on 115.4.0esr for the launcher and 102.11.0esr for the updater because I
can no longer build it.

app/scripts/fetch_xulrunner

@@ -446,7 +446,7 @@ if [ $BUILD_WIN == 1 ]; then
 	GECKO_VERSION="$GECKO_VERSION_WIN"
 	DOWNLOAD_URL="https://ftp.mozilla.org/pub/firefox/releases/$GECKO_VERSION"
 	
-	for arch in win32 win-x64; do
+	for arch in win32 win-x64 win-aarch64; do
 		xdir=firefox-$arch
 		
 		rm -rf $xdir
@@ -458,6 +458,8 @@ if [ $BUILD_WIN == 1 ]; then
 		else
 			if [ $arch = "win-x64" ]; then
 				curl -O "$DOWNLOAD_URL/win64/en-US/Firefox%20Setup%20$GECKO_VERSION.exe"
+			elif [ $arch = "win-aarch64" ]; then
+				curl -O "$DOWNLOAD_URL/win64-aarch64/en-US/Firefox%20Setup%20$GECKO_VERSION.exe"
 			else
 				curl -O "$DOWNLOAD_URL/$arch/en-US/Firefox%20Setup%20$GECKO_VERSION.exe"
 			fi