Prevent user name and email leakage

Stops user name enumeration and other type of user name and email leakages.

Specifically does the following:
1. When the site is configured to use pretty permalinks, the plugin will prevent
the automatic redirect of usrl which include user ID, like example.com/?author=1, to
something like example.com/author/admin which will leak the existence of a user
named admin which can be used in further brute force attacks.
(This is also know as “user enumeration”).

1. With the REST API restrict user name related information (actual user name
   and user posts page URL) to only admin users.

2. Preventing authentication failure notices on the login page to disclose
   the existence of user names/user emails resulting from displaying different
   messages hen the user is incorrect and whe…