Add validation to prevent creation of blank/empty notes

Problem/Motivation

Poor user experience when accidentally creating blank notes

Steps to reproduce

While adding/editing a note make the prompt blank and click on "OK".

Proposed resolution

Technical Limitation:Browser's native prompt() function doesn't support custom button states or validation.
Add input validation logic and blank prompt to alert: "Oops! Looks like you forgot to add the note text."

Remaining tasks

Add the prompt validation with the alert and raise the PR.

User interface changes

A new alert for prompt's input validation.

API changes

N/A

Data model changes

N/A