refactor: alert closing, edit alert, confirmation for deletion

[vens8]

This PR gives feature as follows:

• [x] Added edit icon for alert element, fixed CSS
• [x] Fixed close button functionality for alerts
• [x] Replaced the edit and delete button text with icons
• [x] Added event listener for saving an edit for a task
• [x] Added confirmation dialog before deleting task.

"open-source is work of choice" :)

Resolves #43

[vens8]

Looks like the following now:

Edit saved alert:

[vens8]

@malivinayak Kindly review and approve.