Appointment Dashboard - Add notifications for new appointments

[5hraddha]

Description

As part of this PR, I've:

• added color codes to status badges

• added feature such that no of new appointments are shown in All, Emergency and Normal tabs for the current logged in admin.

• When an admin logs in, if there are any new appointment request, a toast is triggered to show the number of new appointments to work on.
• The new appointments are highlighted on the dashboard to inform the admin. The highlight goes away when the admin clicks and views the appointment.
• If an admin is already logged in and a new appointment request is made, the dashboard updates in realtime highlighting the new request and a toast notification is triggered to inform the admin.
• Removed the separate API calls for each type of appointment. Now, we have only one API call and the rest is taken care by the code.
• Added modified date column to the DB
• Updated the code such that the appointments in the Scheduled and Cancelled Tabs are sorted by modified date column as it seems more logical.

Related Issue

Closes #120 and #115

Acceptance Criteria

• No of new appointments should be shown in each tab for the current logged in admin.
• Toast probably for any new Emergency appointments.
• If the appointment is new, it should appear in bold in the dashboard to for users to differentiate visually.
• Currently, there's no distinct color scheme to visually distinguish between various appointment tags. It would significantly enhance the user experience to assign unique colors to each tag category.

Type of Changes

	Type
	🐛 Bug fix
✓	✨ New feature
	🔨 Refactoring
	💯 Add tests
	🔗 Update dependencies
	📜 Docs

Updates

Before

After

dashboard_notification.mp4

Note for release in production

Since we're creating a new column in DB, we have to manually setup modified_at values to created_at column initially, to keep the values proper. There on, the code will take care.

[mentalcaries]

Excellent work with this one Shradda!