DEV: Modernise csv-uploader component

- remove uppy mixin
- native class
- glimmer component
- gjs file format

assets/javascripts/discourse/components/csv-uploader.gjs

@@ -0,0 +1,66 @@
+import Component from "@glimmer/component";
+import { getOwner } from "@ember/owner";
+import didInsert from "@ember/render-modifiers/modifiers/did-insert";
+import { inject as service } from "@ember/service";
+import { or } from "truth-helpers";
+import UppyUpload from "discourse/lib/uppy/uppy-upload";
+import icon from "discourse-common/helpers/d-icon";
+import i18n from "discourse-common/helpers/i18n";
+
+export default class CsvUploader extends Component {
+  @service dialog;
+
+  uppyUpload = new UppyUpload(getOwner(this), {
+    type: "csv",
+    id: "discourse-post-event-csv-uploader",
+    autoStartUploads: false,
+    uploadUrl: this.args.uploadUrl,
+    uppyReady: () => {
+      this.uppyUpload.uppyWrapper.uppyInstance.on("file-added", () => {
+        this.dialog.confirm({
+          message: i18n(`${this.args.i18nPrefix}.confirmation_message`),
+          didConfirm: () => this.uppyUpload.startUpload(),
+          didCancel: () => this.uppyUpload.reset(),
+        });
+      });
+    },
+    uploadDone: () => {
+      this.dialog.alert(i18n(`${this.args.i18nPrefix}.success`));
+    },
+    validateUploadedFilesOptions: {
+      csvOnly: true,
+    },
+  });
+
+  get uploadButtonText() {
+    return this.uppyUpload.uploading
+      ? i18n("uploading")
+      : i18n(`${this.args.i18nPrefix}.text`);
+  }
+
+  get uploadButtonDisabled() {
+    // https://github.com/emberjs/ember.js/issues/10976#issuecomment-132417731
+    return this.uppyUpload.uploading || this.uppyUpload.processing
+      ? true
+      : null;
+  }
+
+  <template>
+    <span>
+      <label class="btn" disabled={{this.uploadButtonDisabled}}>
+        {{icon "upload"}}&nbsp;{{this.uploadButtonText}}
+        <input
+          {{didInsert this.uppyUpload.setup}}
+          class="hidden-upload-field"
+          disabled={{this.uppyUpload.uploading}}
+          type="file"
+          accept=".csv"
+        />
+      </label>
+      {{#if (or this.uppyUpload.uploading this.uppyUpload.processing)}}
+        <span>{{i18n "upload_selector.uploading"}}
+          {{this.uppyUpload.uploadProgress}}%</span>
+      {{/if}}
+    </span>
+  </template>
+}

assets/javascripts/discourse/components/modal/post-event-bulk-invite.hbs

@@ -84,7 +84,6 @@
         <BulkInviteSampleCsvFile />
 
         <CsvUploader
-          @id="discourse-post-event-csv-uploader"
           @uploadUrl={{concat
             "/discourse-post-event/events/"
             @model.event.id