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/dashboard/components/widgets/conversation/ConversationCard.vue

@@ -120,7 +120,6 @@ import { mapGetters } from 'vuex';
 import Thumbnail from '../Thumbnail.vue';
 import MessagePreview from './MessagePreview.vue';
 import conversationMixin from '../../../mixins/conversations';
-import timeMixin from '../../../mixins/time';
 import router from '../../../routes';
 import { frontendURL, conversationUrl } from '../../../helper/URLHelper';
 import InboxName from '../InboxName.vue';
@@ -144,7 +143,7 @@ export default {
     SLACardLabel,
   },
 
-  mixins: [inboxMixin, timeMixin, conversationMixin, alertMixin],
+  mixins: [inboxMixin, conversationMixin, alertMixin],
   props: {
     activeLabel: {
       type: String,