AWS::IAM::PasswordPolicy

## 2. Scope of request
Allow IAM Password Policy to be set with native CFN versus requiring a lambda + custom resource to call the IAM API directly.

## 3. Expected behavior
I should be able to set an account's password policy without needing to call the API directly.

## 5. Helpful Links to speed up research and evaluation
Functionality appears to be missing based on https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/AWS_IAM.html

Ended up using https://github.com/widdix/aws-cf-templates/blob/master/security/account-password-policy.yaml as a resource to create this stack.

## 6. Category (required) - Will help with tagging and be easier to find by other users to +1
Security

Start with the AWS CloudFormation IAM resource documentation linked in the issue and compare it with the referenced account-password-policy.yaml custom-resource template. Confirm the missing native resource and its required password-policy properties; done means an account password policy can be declared directly in CloudFormation without a Lambda or custom resource.

Written by the indexing model from the issue text.