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/AutomationFileInput.vue

@@ -26,13 +26,12 @@
 </template>
 
 <script>
+import { useAlert } from 'dashboard/composables';
 import Spinner from 'shared/components/Spinner.vue';
-import alertMixin from 'shared/mixins/alertMixin';
 export default {
   components: {
     Spinner,
   },
-  mixins: [alertMixin],
   props: {
     value: {
       type: Array,
@@ -71,7 +70,7 @@ export default {
       } catch (error) {
         this.uploadState = 'failed';
         this.label = this.$t('AUTOMATION.ATTACHMENT.LABEL_UPLOAD_FAILED');
-        this.showAlert(this.$t('AUTOMATION.ATTACHMENT.UPLOAD_ERROR'));
+        useAlert(this.$t('AUTOMATION.ATTACHMENT.UPLOAD_ERROR'));
       }
     },
   },