[Feature]: Allow Signup only with Recognized Email Services

[smog-root]

Update the existing signup and login processes to incorporate email domain validation. Restrict access to users with email addresses from trusted providers (e.g., Gmail, Outlook).

During signup, extract the domain from the user's email address and compare it to a predefined list of approved providers. If the domain matches, proceed with the signup; if it doesn't, show an error message.

i'm expecting a gssoc-ext with level3 and a hacktoberfest-accepted label!

@VesperAkshay

[github-actions[bot]]

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