Admin Portal Opt-Out of Username Case Sensitivity

[allisonnokes]

Describe the problem to be solved

In the current release of PeerTube, email address usernames are case-sensitive. Issue discussed further here: #4103.

This is a user-experience problem for the vast majority of users. None of the major email service providers—such as Gmail, Yahoo Mail, Outlook.com, and others—treat email addresses as case-sensitive. They all normalize email addresses to lower case (or treat them in a case-insensitive manner) for the purposes of account creation, login, and sending/receiving messages.

When logging in to PeerTube, the default behavior from a mobile device is to type a capital letter at the beginning of any string. So notifying the user with a tool-tip or error-handling messaging makes it the user's responsibility to correct two different industry standards which cause the error (1. capitalizing the first letter of a string and 2. Email addresses before the domain name are case-insensitive). Correcting one letter on a mobile device login screen is especially problematic for middle-aged and older users.

Describe the solution you would like

It would be great to offer the option in the admin portal - for a choice to be made regarding the enforcement or not of user name case sensitivity. This would allow PeerTube (in general) to continue to follow industry standards related to case sensitivity as a default, but allow individual instances to opt-out of email address case sensitivity if desired.

[StojanJovanov]

As a QA engineer I do agree with @allisonnokes
I think this is not a UI change but functional change since we are testing log In feature.
Changing the letter in web page might be UI but this is kind of functional :)
Best regards,
Stole Jovanov

[MattyBoombalatty]

This also causes issues with logins using OAUTH. Usernames on Pleroma instances with capitals in their handles will break, and not allow login.