meta-ampere: Support Ampere password policy

Implement Ampere password policy as followings:
 - Password must between 9-20 characters, 1 lower case, 1 upper case,
   one digit and 1 special character.
 - No more than 3 consecutive identical characters.

Signed-off-by: Hieu Huynh <hieuh@os.amperecomputing.com>
Change-Id: I20134f51e06ef0aabeddfc4d1560acfa7483deab