feat: Replace alertMixin usage with useAlert (#9793)

# Pull Request Template

## Description

This PR will replace the usage of `alertMixin` from the code base with
the `useAlert` composable.

Fixes
https://linear.app/chatwoot/issue/CW-3462/replace-alertmixin-usage-with-usealert

## Type of change

- [x] Breaking change (fix or feature that would cause existing
functionality not to work as expected)

## How Has This Been Tested?

Please refer this issue description

https://linear.app/chatwoot/issue/CW-3462/replace-alertmixin-usage-with-usealert


## Checklist:

- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [ ] 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/bubble/Contact.vue

@@ -17,14 +17,13 @@
 </template>
 
 <script>
+import { useAlert } from 'dashboard/composables';
 import {
   DuplicateContactException,
   ExceptionWithMessage,
 } from 'shared/helpers/CustomErrors';
-import alertMixin from 'shared/mixins/alertMixin';
 
 export default {
-  mixins: [alertMixin],
   props: {
     name: {
       type: String,
@@ -52,18 +51,18 @@ export default {
             'contacts/create',
             this.getContactObject()
           );
-          this.showAlert(this.$t('CONTACT_FORM.SUCCESS_MESSAGE'));
+          useAlert(this.$t('CONTACT_FORM.SUCCESS_MESSAGE'));
         }
         this.openContactNewTab(contact.id);
       } catch (error) {
         if (error instanceof DuplicateContactException) {
           if (error.data.includes('phone_number')) {
-            this.showAlert(this.$t('CONTACT_FORM.FORM.PHONE_NUMBER.DUPLICATE'));
+            useAlert(this.$t('CONTACT_FORM.FORM.PHONE_NUMBER.DUPLICATE'));
           }
         } else if (error instanceof ExceptionWithMessage) {
-          this.showAlert(error.data);
+          useAlert(error.data);
         } else {
-          this.showAlert(this.$t('CONTACT_FORM.ERROR_MESSAGE'));
+          useAlert(this.$t('CONTACT_FORM.ERROR_MESSAGE'));
         }
       }
     },