Pending user email check must be case insensitive

[mjtravers]

Business Reason

As a user, I will be able to select a committee that I've been assigned to when my registered email does not match the letter case of the email that the committee administrator enters into the system.

Acceptance Criteria

If A user email registered with Login.gov does not match the case of the email entered into the committee user list by a committee administrator

When the user logs in and views the list of committees to select

Then the user will see all the committees assigned to them even if the email entered by the committee administrator did not match the letter case of the user's registered email.

QA Notes

To test, have your login assigned a new committee using an email that does not match the letter case of the email used at Login.gov.

DEV Notes

Here is the line of code that needs the "__iexact" Django field lookup to fix the bug: https://github.com/fecgov/fecfile-web-api/blob/release/sprint-43/django-backend/fecfiler/user/managers.py#L14

Here is an example of code that does the correct case insensitive lookup: https://github.com/fecgov/fecfile-web-api/blob/release/sprint-43/django-backend/fecfiler/committee_accounts/views.py#L170

Be sure to write a unit test to cover this test case.

Design

null

[WiseQA]

QA review verified with DEV this bug, as ticket written by DEV to explain issue correctly.

[mjtravers]

Passes CR. Sending to QA.

[WiseQA]

QA review visual inspection with DEV on the assigned a new committee using an email that does not match the letter case of the email used at Login.gov.

QA Review Completed. Moved to Stage Ready.