Update definitions

[a2ush]

Issue #, if available:
#103
#102

Description of changes:

Support the following type:

• AWS::IAM::User[1]
• AWS::IAM::Policy
• AWS::IAM::AccessKey
• AWS::SecretsManager::Secret
• AWS::S3::Bucket
• AWS::RDS::DBCluster
• AWS::RDS::DBInstance
  etc...

[1] Currently, AWS does not provide "IAM User" icon[2], so I try to match this resource type to "General User" icon.
[2] https://aws.amazon.com/architecture/icons/?nc1=h_ls

Diagram:
  DefinitionFiles:
     ...
  Resources:
    Canvas:
      Type: AWS::Diagram::Canvas
      Direction: vertical
      Children:
        - AWSCloud
    AWSCloud:
      Type: AWS::Diagram::Cloud
      Direction: vertical
      Preset: AWSCloudNoLogo
      Align: center
      Children:
        - IAMStack
        - Secrets
        - S3
        - Aurora
        - DbInstance
    IAMStack:
      Type: AWS::Diagram::HorizontalStack
      Children:
        - IAMUser
        - IAMPolicy      
        - IAMAccessKey
    IAMUser:
      Type: AWS::IAM::User
    IAMPolicy:
      Type: AWS::IAM::Policy
    IAMAccessKey:
      Type: AWS::IAM::AccessKey      
    S3:
      Type: AWS::S3::Bucket
    Aurora:
      Type: AWS::RDS::DBCluster
    DbInstance:
      Type: AWS::RDS::DBInstance
    Secrets:
      Type: AWS::SecretsManager::Secret

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