Implement setRequiredPasswordComplexity

Implement setRequiredPasswordComplexity and
getRequiredPasswordComplexity, which enforce password requiremets
according to one of four, platform-defined complexity levels.

Start adjusting the platform to take the complexity into account:
* isActivePasswordSufficient would return false if complexity is set
  but the current password does not meet the complexity criteria.
* resetPasswordWithToken would not allow resetting the password to a
  value that does not meet the complexity criteria.

Bug: 165573442
Test: atest FrameworksServicesTests:DevicePolicyManagerTest
Test: atest com.android.cts.devicepolicy.MixedDeviceOwnerTest#testResetPasswordWithToken
Change-Id: I4e66af0b03c521de70bba3192751164736d01c62