The new user registration form is not accessible to users using a screen reader

[Andrea-Guevara]

Describe the bug

The new user registration form is not accessible to users using a screen reader.

To reproduce

Steps to reproduce the behavior:

1. Using a screen reader, go to the log in area.
2. Click on “New user? Click here to register”.
3. Navigate through the “New user registration” page and check that the screen reader doesn't clearly tell the user what to do, or even can't identify the error messages.

Expected behavior

The functionalities of the page could be more accessible and intuitive for users who use a screen reader. For example: a better description of what the user needs to do, error messages need to be identified by the screen reader and even if disabled the “register” button needs to be accessible.

Related work

#3272

New consideration: as the “ds-base-register-email-form” component is used in “New user registration” and “Forgot password”, this implementation already deals with the accessibility problem in general.