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/WootWriter/FullEditor.vue

@@ -24,7 +24,7 @@ import {
   Selection,
 } from '@chatwoot/prosemirror-schema';
 import { checkFileSizeLimit } from 'shared/helpers/FileHelper';
-import alertMixin from 'shared/mixins/alertMixin';
+import { useAlert } from 'dashboard/composables';
 import keyboardEventListenerMixins from 'shared/mixins/keyboardEventListenerMixins';
 import uiSettingsMixin from 'dashboard/mixins/uiSettings';
 
@@ -51,7 +51,7 @@ const createState = (
 };
 
 export default {
-  mixins: [keyboardEventListenerMixins, uiSettingsMixin, alertMixin],
+  mixins: [keyboardEventListenerMixins, uiSettingsMixin],
   props: {
     value: { type: String, default: '' },
     editorId: { type: String, default: '' },
@@ -108,7 +108,7 @@ export default {
       if (checkFileSizeLimit(file, MAXIMUM_FILE_UPLOAD_SIZE)) {
         this.uploadImageToStorage(file);
       } else {
-        this.showAlert(
+        useAlert(
           this.$t('HELP_CENTER.ARTICLE_EDITOR.IMAGE_UPLOAD.ERROR_FILE_SIZE', {
             size: MAXIMUM_FILE_UPLOAD_SIZE,
           })
@@ -127,13 +127,9 @@ export default {
         if (fileUrl) {
           this.onImageUploadStart(fileUrl);
         }
-        this.showAlert(
-          this.$t('HELP_CENTER.ARTICLE_EDITOR.IMAGE_UPLOAD.SUCCESS')
-        );
+        useAlert(this.$t('HELP_CENTER.ARTICLE_EDITOR.IMAGE_UPLOAD.SUCCESS'));
       } catch (error) {
-        this.showAlert(
-          this.$t('HELP_CENTER.ARTICLE_EDITOR.IMAGE_UPLOAD.ERROR')
-        );
+        useAlert(this.$t('HELP_CENTER.ARTICLE_EDITOR.IMAGE_UPLOAD.ERROR'));
       }
     },
     onImageUploadStart(fileUrl) {