DEV: prep for gjs conversion: rename .js -> .gjs

Some of these files are quite small, and if we rename them in the same
commit where we inlined the template, Git may choose to see them as
different files. This commit forces Git to recognize the rename, which
will preserve the lineage of the refactored files.

plugins/chat/assets/javascripts/discourse/components/chat-message-thread-indicator.gjs

@@ -0,0 +1,86 @@
+import Component from "@glimmer/component";
+import { tracked } from "@glimmer/tracking";
+import { action } from "@ember/object";
+import { inject as service } from "@ember/service";
+import { bind } from "discourse-common/utils/decorators";
+
+export default class ChatMessageThreadIndicator extends Component {
+  @service capabilities;
+  @service chat;
+  @service chatStateManager;
+  @service router;
+  @service site;
+
+  @tracked isActive = false;
+
+  @action
+  setup(element) {
+    this.element = element;
+
+    if (this.capabilities.touch) {
+      this.element.addEventListener("touchstart", this.onTouchStart, {
+        passive: true,
+      });
+      this.element.addEventListener("touchmove", this.cancelTouch, {
+        passive: true,
+      });
+      this.element.addEventListener("touchend", this.onTouchEnd);
+      this.element.addEventListener("touchCancel", this.cancelTouch);
+    }
+
+    this.element.addEventListener("click", this.openThread, {
+      passive: true,
+    });
+  }
+
+  @action
+  teardown() {
+    if (this.capabilities.touch) {
+      this.element.removeEventListener("touchstart", this.onTouchStart, {
+        passive: true,
+      });
+      this.element.removeEventListener("touchmove", this.cancelTouch, {
+        passive: true,
+      });
+      this.element.removeEventListener("touchend", this.onTouchEnd);
+      this.element.removeEventListener("touchCancel", this.cancelTouch);
+    }
+
+    this.element.removeEventListener("click", this.openThread, {
+      passive: true,
+    });
+  }
+
+  @bind
+  onTouchStart(event) {
+    this.isActive = true;
+    event.stopPropagation();
+
+    this.touching = true;
+  }
+
+  @bind
+  onTouchEnd() {
+    this.isActive = false;
+
+    if (this.touching) {
+      this.openThread();
+    }
+  }
+
+  @bind
+  cancelTouch() {
+    this.isActive = false;
+    this.touching = false;
+  }
+
+  @bind
+  openThread() {
+    this.chat.activeMessage = null;
+
+    this.router.transitionTo(
+      "chat.channel.thread",
+      ...this.args.message.thread.routeModels
+    );
+  }
+}