Fix registration testing points

After testing, these are the things to fix:

[x] Change label of button for provisioning users. Not important but it saying Sign In is weird.
[x] Make buttons for Login and Registration pages more obvious, show distinction between them to show which page the user is currently on. [BUTTONS WILL BE CHANGED AFTER DESIGN IS MADE ON FIGMA]
[x] Change the "Username" label to "Display Name / Tag". Allow spaces in the field. No leading/trailing spaces and underscores, no neighboring spaces and underscors (i.e. _, , )
[x] Add an area under the form field that shows the resulting username (i.e. lowercase, spaces replaced with underscores).
[x] If 400 response "4: Posted email does not match the email of the provisioned user." then handle as error display under the Email field of registration.
[x] Add pronoun options: He/They, She/They, Any/All, and Other.
[x] Preffered Name and City (when shown) are not considered optional fields and will prevent submission. The 3rd region dropdown is currently optional though, state/province should be required when applicable.
[x] Successfully submitting user details does not redirect from the page. It should either go back to the previous page unless its the login page, in which case it should go to homepage/index (i.e. dashboard).
[x] The formatting of the form could user some adjusting (see pin). Form entry fields dont need to be so wide. Checkboxes just need to say "Private" to the right of it, should be clear what is private when inline/grouped with a field. This is more of a polish job, can be saved for when theres nothing else to do but I think the stuff above is more pressing, as well as working on frontend for other pages and functionality. [THIS WILL BE CHANGED AFTER DESIGN IS MADE ON FIGMA]

luismr00 / emblems_client

Fix registration testing points #7