AWS::SSM::Parameter - Type-SecureString

## 1. Title - AWS::SSM::Parameter-Type-SecureString

## 2. Scope of request

When creating a new SSM Parameter resource you can create using the String and StringList Type however not SecureString.

This is currently possible with additional lambda functions within the template however it will make for easier to follow templates for both parameter creation and dynamic linking to ssm parameters.

We use SSM Parameters for variables, including sensitive data, so the ability to continue utilising these without manual creation before a stack deployment is desired.

Sample:
#### AWS::SSM::Parameter-Type-SecureString supports String and StringList but not SecureString.

## 3. Expected behaviour

As part of the Console or API, we can create a new SecureString Parameter. It's expected that CloudFormation should also include this functionality.

## 4. Suggest specific test cases

Common use case: Creating a securestring parameter during stack creation from inputted parameters. These parameters can then be dynamically referenced throughout the stack.

Test case recommendation: Ability to create a securestring value and reference it from the same stack.

## 5. Helpful Links to speed up research and evaluation

Reference Doc detailing the feature doesn't yet exist. https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-ssm-parameter.html

## 6. Category

Management - Systems Manager

## 7. Any additional context (optional)

We currently get around this using 3 ways:

1. Manual SecureString Parameter creation pre stack create.
2. Addition lambda function to create the secure parameter (Add complexity to the template).
3. Create and use Secrets Manager. (This works well however at scale the cost of Secrets Manager become prohibitive)