Add Note to Budget Command

[Kimiti4]

This PR will add a new CQRS command and handler to 'Add Note to Budget'.

• AddNoteToBudgetCommand`: encapsulates the budget ID, content, and creator.

• AddNoteToBudgetHandler: it will validate pull request (PR) implements a new Command and Handler for adding notes to a budget.

• AddNoteToBudgetCommand: Encapsulates the budget ID, note content, and creator information.

• AddNoteToBudgetHandler: Validates the command data and calls the repository to persist the note.

Design Choices:

• Follows the CQRS pattern for clear command-query separation.
• Utilizes a repository abstraction for efficient serverless deployment.
• Designed to scale automatically in a serverless architecture like Firebase Functions.This pull request (PR) implements a new Command and Handler for adding notes to a budget.