authentication attributes.

This WL implements the following:
  1. Separation of authentication from authorization. GRANT statement
     deals with both authorization and authentication. This WL deprecates
     the authentication part from GRANT statement by throwing a warning.
  2. CREATE/ALTER USER statements will be used to provide authentication
     details associated with a user. GRANT statement when used to create
     users will throw a deprecated warning.
  3. PASSWORD() function is removed from SET PASSWORD sytax.
  4. Authentication plugin is extended to add 2 new APIs which will generate
     and validate password hash without depending on old_password variable anymore.
  5. New system variable to ensure backward compatibility when user management
     queries are rewritten to logs (slow/general/audit/binary logs).
  6. New Plugin services to validate/calculate_strength/set_salt for
     the credentials.
  7. ALTER US...