Generate zip files before download

Previously, zip files were only downloaded if they already
existed. Now, they are created with  an action, then
downloaded from the result.

Chrome now insists on downloading the files as `output.zip`, I can't see why this has changed, but perhaps it's related
to the security warning. This seems to be specific to zip files.

webapp/src/components/tabContentComponents/scanListContent.vue

@@ -42,13 +42,15 @@
           <div class="uk-card">
             <div class="uk-card-body">
               <h3 class="uk-card-title">{{ item.name }}</h3>
-              <a
-                :href="`${scansUri}/${item.name}/images.zip`"
-                :download="`${item.name}_images.zip`"
-                class="uk-button uk-button-default"
-              >
-                Download images
-              </a>
+              <task-submitter
+                submit-label="Download ZIP"
+                :can-terminate="false"
+                :submit-data="{'scan_name': item.name}"
+                :button-primary="true"
+                :submit-url="createZipOfScanUri"
+                @response="downloadZipFile"
+                @error="modalError"
+              />
               <button class="uk-button" @click="deleteScan(item.name)">
                 Delete
               </button>
@@ -73,9 +75,11 @@
 
 <script>
 import axios from "axios";
+import taskSubmitter from '../genericComponents/taskSubmitter.vue';
 
 // Export main app
 export default {
+  components: { taskSubmitter },
   name: "ScanListContent",
 
   data: function() {
@@ -92,6 +96,9 @@ export default {
         "readproperty",
         true
       );
+    },
+    createZipOfScanUri() {
+      return this.thingActionUrl("smart_scan",  "create_zip_of_scan");
     }
   },
 
@@ -186,6 +193,17 @@ export default {
         // if the confirmation was cancelled, it's rejected with null error
         if (e) this.modalError(e);
       }
+    },
+    async downloadZipFile(response) {
+      const scan_name = response.input.scan_name;
+      const filename = `${scan_name}_images.zip`
+      const url = response.output.href;
+      const link = document.createElement("a");
+      link.href = url;
+      link.setAttribute("download", filename);
+      console.log(link);
+      document.body.appendChild(link);
+      link.click();
     }
   }
 };