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/MaskedText.vue

@@ -18,10 +18,9 @@
 <script>
 import 'highlight.js/styles/default.css';
 import { copyTextToClipboard } from 'shared/helpers/clipboard';
-import alertMixin from 'shared/mixins/alertMixin';
+import { useAlert } from 'dashboard/composables';
 
 export default {
-  mixins: [alertMixin],
   props: {
     value: {
       type: String,
@@ -37,7 +36,7 @@ export default {
     async onCopy(e) {
       e.preventDefault();
       await copyTextToClipboard(this.value);
-      this.showAlert(this.$t('COMPONENTS.CODE.COPY_SUCCESSFUL'));
+      useAlert(this.$t('COMPONENTS.CODE.COPY_SUCCESSFUL'));
     },
     toggleMasked() {
       this.masked = !this.masked;