Move event handling to lit-element and re-enable the loading spinner again

This way lit-element manages the event bindings when the upload component gets
connected.

src/vpu-official-signature-pdf-upload.js

@@ -57,14 +57,6 @@ class OfficialSignaturePdfUpload extends ScopedElementsMixin(VPUSignatureLitElem
 
     connectedCallback() {
         super.connectedCallback();
-
-        this.updateComplete.then(()=>{
-            const fileUpload = this._("#file-upload");
-            fileUpload.addEventListener('vpu-fileupload-all-start', this.onAllUploadStarted.bind(this));
-            fileUpload.addEventListener('vpu-fileupload-file-start', this.onFileUploadStarted.bind(this));
-            fileUpload.addEventListener('vpu-fileupload-file-finished', this.onFileUploadFinished.bind(this));
-            fileUpload.addEventListener('vpu-fileupload-all-finished', this.onAllUploadFinished.bind(this));
-        });
     }
 
     /**
@@ -294,8 +286,7 @@ class OfficialSignaturePdfUpload extends ScopedElementsMixin(VPUSignatureLitElem
 
     render() {
         if (this.isLoading()) {
-            // TODO: breaks upload (added in commit 5dbb3033b4c37ebfb5810d78ed9522047217490d)
-            // return html`<vpu-mini-spinner></vpu-mini-spinner>`;
+            return html`<vpu-mini-spinner></vpu-mini-spinner>`;
         }
         return html`
             <div class="${classMap({hidden: !this.isLoggedIn() || !this.hasSignaturePermissions()})}">
@@ -303,7 +294,13 @@ class OfficialSignaturePdfUpload extends ScopedElementsMixin(VPUSignatureLitElem
                     <h2>${i18n.t('official-pdf-upload.upload-field-label')}</h2>
                     <div class="control">
                         <vpu-fileupload id="file-upload" lang="${this.lang}" url="${this.signingUrl}" accept="application/pdf"
-                            text="${i18n.t('official-pdf-upload.upload-area-text')}" button-label="${i18n.t('official-pdf-upload.upload-button-label')}"></vpu-fileupload>
+                            text="${i18n.t('official-pdf-upload.upload-area-text')}"
+                            button-label="${i18n.t('official-pdf-upload.upload-button-label')}"
+                            @vpu-fileupload-all-start="${this.onAllUploadStarted}"
+                            @vpu-fileupload-file-start="${this.onFileUploadStarted}"
+                            @vpu-fileupload-file-finished="${this.onFileUploadFinished}"
+                            @vpu-fileupload-all-finished="${this.onAllUploadFinished}"
+                            ></vpu-fileupload>
                     </div>
                 </div>
                 <div class="field notification is-info ${classMap({hidden: !this.uploadInProgress})}">