Add missing CLI utilities to libvips.libvips 8.16.1 (microsoft#333230)

Author: kleisauke

manifests/l/libvips/libvips/8.16.1/libvips.libvips.installer.yaml

@@ -9,6 +9,10 @@ NestedInstallerType: portable
 NestedInstallerFiles:
   - RelativeFilePath: vips-dev-8.16/bin/vips.exe
     PortableCommandAlias: vips
+  - RelativeFilePath: vips-dev-8.16/bin/vipsheader.exe
+    PortableCommandAlias: vipsheader
+  - RelativeFilePath: vips-dev-8.16/bin/vipsthumbnail.exe
+    PortableCommandAlias: vipsthumbnail
 InstallModes:
   - interactive
   - silent