User email should not be case sensitive

Problem/Motivation

If a user registers an account using capital letters in their email address, to be able to reset their password later they need to enter email with exact same capitalization. If they enter email as all lowercase or a different capitalization from original, they aren't able to reset their password.

(I suspect there should be a duplicate issue, but wasn't able to find it).

Proposed resolution

User email should not be case sensitive

Remaining tasks

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User interface changes

API changes