* feat: Returns an error on join request with no display name.

When someone tries to join a room with lobby enabled and display name is not set returns an error.

* squash: Fixes handling DISPLAY_NAME_REQUIRED with preJoin disabled.

* squash: Fixes mobile build.

* squash: Move isDisplayNameRequired redux state in lobby and introduces isDisplayNameRequiredError.

* squash: Drops unused isDisplayNameRequired.

This was used on showing prejoin when connection was established on showing prejoin. We no longer establish it at that time, so it is not possible to hit it and act on it.