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/SnackbarContainer.vue

@@ -15,13 +15,11 @@
 
 <script>
 import WootSnackbar from './Snackbar.vue';
-import alertMixin from 'shared/mixins/alertMixin';
 
 export default {
   components: {
     WootSnackbar,
   },
-  mixins: [alertMixin],
   props: {
     duration: {
       type: Number,
@@ -42,7 +40,7 @@ export default {
     this.$emitter.off('newToastMessage', this.onNewToastMessage);
   },
   methods: {
-    onNewToastMessage(message, action) {
+    onNewToastMessage({ message, action }) {
       this.snackMessages.push({
         key: new Date().getTime(),
         message,