CI: allow libpack builds to be triggered via githubs workflow_dispatch (#26742)

.github/workflows/sub_buildWindows.yml

@@ -24,15 +24,27 @@
 
 name: Build Windows
 on:
+  workflow_dispatch:
+    inputs:
+      artifactBasename:
+        description: "Base name for artifact"
+        required: false
+        type: string
+        default: "FreeCAD"
+      allowedToFail:
+        description: "whether a failed build is allowed"
+        required: false
+        type: boolean
+        default: false
   workflow_call:
     inputs:
       artifactBasename:
-        type: string
         required: true
+        type: string
       allowedToFail:
+        required: false
         default: false
         type: boolean
-        required: false
     outputs:
       reportFile:
         value: ${{ jobs.Build.outputs.reportFile }}