set email validator to lowercase

[bglidwell]

Description of what you did:

Yup .lowercase() converts the string to lowercase which should be done in all instances of email across the application.

Fixes bug where users created inside Strapi admin panel end up with mixed case emails in database.

[codecov]

Codecov Report

Merging #7645 into master will increase coverage by 0.03%.
The diff coverage is 58.82%.

@@            Coverage Diff             @@
##           master    #7645      +/-   ##
==========================================
+ Coverage   27.16%   27.20%   +0.03%     
==========================================
  Files        1163     1164       +1     
  Lines       15518    15519       +1     
  Branches     2410     2412       +2     
==========================================
+ Hits         4216     4222       +6     
+ Misses       9534     9528       -6     
- Partials     1768     1769       +1     

Flag	Coverage Δ
#front	19.36% <62.50%> (+0.04%)	⬆️
#unit	53.85% <0.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...admin/admin/src/components/ContainerFluid/index.js	66.66% <ø> (ø)
...in/src/components/LeftMenu/LeftMenuFooter/index.js	33.33% <0.00%> (-33.34%)	⬇️
...trapi-admin/admin/src/validations/users/profile.js	50.00% <ø> (ø)
...kages/strapi-admin/validation/common-validators.js	79.16% <ø> (ø)
...rc/containers/EditViewDataManagerProvider/index.js	0.00% <0.00%> (ø)
.../admin/src/components/ComponentIconPicker/index.js	0.00% <0.00%> (ø)
...agerProvider/utils/retrieveComponentsFromSchema.js	68.75% <ø> (ø)
...ugin-upload/admin/src/components/EditForm/index.js	0.00% <0.00%> (ø)
...rapi-plugin-upload/admin/src/translations/index.js	0.00% <ø> (ø)
packages/strapi-provider-upload-local/lib/index.js	29.16% <0.00%> (ø)
... and 5 more

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[soupette]

@bglidwell thanks a lot for your contribution! Before reviewing your PR can you make sure the DCO checks?
Also, do you mind updating the front-end validations so it matches the back-end ones? Here's the corresponding file

[bglidwell]

@soupette done!

[soupette]

LGTM to me for the front-end part.

[bglidwell]

Worth noting, this optimization can be used in a lot of different areas. I scoped this particular PR to just the users & permissions plugin for simplicity. I think this route makes schemas easier to test.

[bglidwell]

Interesting that the backend doesn't also use yup for validation. Seems a lot of that could be shared between FE/BE, reducing complexity and improving consistency.

It appears the admin panel uses a different controller, so that needed to be updated with toLowerCase() as well. I feel the plugin itself could use some more work.

[soupette]

LGTM