support password reset with case-insensitive email address

[RabiaSajjad]

Fixes #

Proposed fixes:

• Support password reset requests using case-insensitive email addresses.
• Ensures users can reset their password even if their email is stored with mixed-case letters.

Features:

• includes tests covering changes
• includes updated documentation
• includes user-visible changes
• includes API changes
• includes bugfix for possible backport

Please [X] all the boxes above that apply

[JVickery-TBS]

@RabiaSajjad just the 2 minor nit picky things

[JVickery-TBS]

@RabiaSajjad idk why it is screaming about merge conflict, but this looks good!