Add GSIs to `DynamoDBCrudPolicy'.

[clickyotomy]

Issue #, if available: #280.
Description of changes:

• Update Resource policy for DynamoDBCrudPolicy:
  • From:

    {
      "Fn::Sub": [
        "arn:${AWS::Partition}:dynamodb:${AWS::Region}:${AWS::AccountId}:table/${tableName}",
        {
          "tableName": {
            "Ref": "TableName"
          }
        }
      ]
    }

  • To:

    {
      "Fn::Sub": [
        "arn:${AWS::Partition}:dynamodb:${AWS::Region}:${AWS::AccountId}:table/${tableName}",
        {
          "tableName": {
            "Ref": "TableName"
          }
        }
      ]
    },
    {
      "Fn::Sub": [
        "arn:${AWS::Partition}:dynamodb:${AWS::Region}:${AWS::AccountId}:table/${tableName}/index/*",
        {
          "tableName": {
            "Ref": "TableName"
          }
        }
      ]
    }

• Update related test case outputs.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[keetonian]

Looks good! And thank you for your contribution!