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/composables/spec/useAdmin.spec.js

@@ -0,0 +1,52 @@
+import { ref } from 'vue';
+import { useAdmin } from '../useAdmin';
+import { useStoreGetters } from 'dashboard/composables/store';
+
+vi.mock('dashboard/composables/store');
+
+describe('useAdmin', () => {
+  it('returns true if the current user is an administrator', () => {
+    useStoreGetters.mockReturnValue({
+      getCurrentRole: ref('administrator'),
+    });
+
+    const { isAdmin } = useAdmin();
+    expect(isAdmin.value).toBe(true);
+  });
+
+  it('returns false if the current user is not an administrator', () => {
+    useStoreGetters.mockReturnValue({
+      getCurrentRole: ref('user'),
+    });
+
+    const { isAdmin } = useAdmin();
+    expect(isAdmin.value).toBe(false);
+  });
+
+  it('returns false if the current user role is null', () => {
+    useStoreGetters.mockReturnValue({
+      getCurrentRole: ref(null),
+    });
+
+    const { isAdmin } = useAdmin();
+    expect(isAdmin.value).toBe(false);
+  });
+
+  it('returns false if the current user role is undefined', () => {
+    useStoreGetters.mockReturnValue({
+      getCurrentRole: ref(undefined),
+    });
+
+    const { isAdmin } = useAdmin();
+    expect(isAdmin.value).toBe(false);
+  });
+
+  it('returns false if the current user role is an empty string', () => {
+    useStoreGetters.mockReturnValue({
+      getCurrentRole: ref(''),
+    });
+
+    const { isAdmin } = useAdmin();
+    expect(isAdmin.value).toBe(false);
+  });
+});