Added noWhitespaceValidator

[mishalsheza]

[#12679] Copying feedback session: Name for copied session should not be whitespace (#12679)

Fixes #12679
Outline of Solution

Added a custom validator to the email field to ensure it does not contain only whitespace.
Custom Validator (noWhitespaceValidator): This validator checks if the input contains only whitespace and returns an error if it does.

Form Group Initialization: Updated the form group initialization in both ngOnInit and resetFormGroups to include the custom validator for the email field.

Error Handling: Ensure that the error messages are handled appropriately in the UI if the validator detects a whitespace-only value.

This approach ensures that any whitespace-only values for the email field are effectively handled both on the client side and before submission.

[github-actions]

Hi @mishalsheza, thank you for your interest in contributing to TEAMMATES!
However, your PR does not appear to follow our contribution guidelines:

• Title must start with the issue number the PR is fixing in square brackets, e.g. [#<issue-number>]

Please address the above before we proceed to review your PR.

[github-actions]

Hi @mishalsheza, thank you for your interest in contributing to TEAMMATES!
However, your PR does not appear to follow our contribution guidelines:

• Title must start with the issue number the PR is fixing in square brackets, e.g. [#<issue-number>]

Please address the above before we proceed to review your PR.

[nusoss-bot]

Folks, This PR seems to be stalling (no activities for the past 7 days). 🐌 😢
Hope someone can get it to move forward again soon...

[nusoss-bot]

Folks, This PR seems to be stalling (no activities for the past 7 days). 🐌 😢
Hope someone can get it to move forward again soon...

[nusoss-bot]

Folks, This PR seems to be stalling (no activities for the past 7 days). 🐌 😢
Hope someone can get it to move forward again soon...