feat: Move timeMixin to a helper (#9799)

# Pull Request Template

## Description

This PR will replace the usage of `timeMixin` with `timeHelper`

Fixes
https://linear.app/chatwoot/issue/CW-3451/move-time-mixin-to-a-helper

## Type of change

- [x] New feature (non-breaking change which adds functionality)

## How Has This Been Tested?

Please refer to this issue description.
https://linear.app/chatwoot/issue/CW-3451/move-time-mixin-to-a-helper

## Checklist:

- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [x] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

---------

Co-authored-by: Sojan Jose <sojan@pepalo.com>

app/javascript/widget/components/UserMessage.vue

@@ -83,7 +83,7 @@ import ImageBubble from 'widget/components/ImageBubble.vue';
 import VideoBubble from 'widget/components/VideoBubble.vue';
 import FluentIcon from 'shared/components/FluentIcon/Index.vue';
 import FileBubble from 'widget/components/FileBubble.vue';
-import timeMixin from 'dashboard/mixins/time';
+import { messageStamp } from 'shared/helpers/timeHelper';
 import messageMixin from '../mixins/messageMixin';
 import ReplyToChip from 'widget/components/ReplyToChip.vue';
 import DragWrapper from 'widget/components/DragWrapper.vue';
@@ -103,7 +103,7 @@ export default {
     ReplyToChip,
     DragWrapper,
   },
-  mixins: [timeMixin, messageMixin],
+  mixins: [messageMixin],
   props: {
     message: {
       type: Object,
@@ -135,7 +135,7 @@ export default {
     },
     readableTime() {
       const { created_at: createdAt = '' } = this.message;
-      return this.messageStamp(createdAt);
+      return messageStamp(createdAt);
     },
     isFailed() {
       const { status = '' } = this.message;