Rename all `username` symbols to `usernameAndPassword`

[infomiho]

In the Wasp file, you specify the Username & password auth method by modifying the usernameAndPassword property.

In a lot of places in auth we refer to this as the username provider e.g. providerName=username in the AuthIdentity or we use it to narrow down types await sanitizeAndSerializeProviderData<'username'>({ ... }), again using username.

For the Email auth method, we are consistent, we are using email in the Wasp file and all of the other places.

What to do

We have the option to:

• change the usernameAndPassword to username in the Wasp file
• change the username everywhere else to usernameAndPassword

I guess the first option makes more sense since it's a better name? Do we then rename the email auth to emailAndPassword?

[Martinsos]

I would probably vote for usernameAndPass and emailAndPass :D.

But I am also ok with other options if people like them better. It is easy for me to be proposing renamings like this form the distance, you will know better what this will look like in practice and if it makes sense.