fix(registrar): allow for uppercase in top level domain of email

Description

fix(registrar): allow for uppercase in top level domain of email

• There are many regexes for domain validation floating around that require the top level domain to be lowercase, however I have not found any reason for it to be so and most email validators accept it uppercase aswell

How to test

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TODO: Add e.g. example usage, screenshots

Related issues

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Closes STR-1507