HEEDLS-903 Make the email in the register admin journey case insensitive

[VladNicol]

JIRA link

HEEDLS-903

Description

For the admin registration journey, make the check that the email provided matches the AutoRegisterManagerEmail case insensitive

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Developer checks

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I have:

• Run the formatter and made sure there are no IDE errors.
• Written tests for the changes (accessibility tests, unit tests for controller, data services, services, view models, etc)
• Manually tested my work with and without JavaScript. Full manual testing guidelines can be found here: https://softwiretech.atlassian.net/wiki/spaces/HEE/pages/6703648740/Testing
• Updated/added documentation in Swiki and/or Readme. Links (if any) are below:
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• Updated my Jira ticket with information about other parts of the system that were touched as part of the MR and have to be sanity tested to ensure nothing’s broken.
• Scanned over my own MR to ensure everything is as expected.

[simonbrent]

As @AlexJacksonDS has noted in Jira, this has been fixed on UAR, but because the DoesEmailMatchCentre method has been moved to a different file on UAR, it will cause a merge conflict next time master is merged into uar-test.