Rename "Customers" to "Name Reservations" in FireStore and code

[sanity]

No description provided.

[sanity]

Or delete "Customers" if it's no-longer relevant.

[Derek52]

The plan was to have one table of reserved usernames, and then one table of email addresses that represent people. This is because an email address can have multiple reservations. "Name Reservations" sounds like it should be the name for the table of reserved usernames.

Technically, we don't need two tables, because everyone's email is stored with their reservation. But, having 2 tables makes it much easier to get a list of every email address, with no duplicates. We also log their email before they finish reserving their username. The second table lets us do that. "Customers" is the wrong name for that table now that I think about it. But, I don't think "Name reservations" is the right one either.

[sanity]

"names"?