AwsCustomResource: When extracting a json field from response, json response seem to be url encoded

### Describe the bug

I have a simple stack, that uses AwsCustomResource to query an IAM role and fetches AssumeRolePolicyDocument field from the response and proceeds to store that in SSM parameter variable

```
export class GetCurrentAssumePoliciesStack extends Stack {
constructor(scope: Construct, id: string, props?: StackProps) {
super(scope, id, props);

const roleName = 'role-that-has-trust-policy'
const getRoleCustomResource = new AwsCustomResource(this, "CustomResourcePolicy", {
resourceType: "Custom::GetIamRoleCustomResourcePolicy",
onCreate: {
service: "IAM",
action: "getRole",
parameters: {
RoleName: roleName,
},
physicalResourceId: PhysicalResourceId.of(roleName),
},
onUpdate: {
service: "IAM",
action: "getRole",
parameters: {
RoleName: roleName,
},
physicalResourceId: PhysicalResourceId.of(roleName),
},
policy: AwsCustomResourcePolicy.fromStatements([
new PolicyStatement({
actions: ["iam:*"],
resources: ["*"],
}),
]),
});

new StringParameter(this, "Parameter", {
parameterName: "/path/to/parameter",
description: "Description for your parameter",
stringValue: getRoleCustomResource.getResponseField("Role.AssumeRolePolicyDocument"),
});
}
}
```

When the stack is deployed, i noticed that the value in SSM Param store for the key /path/to/parameter seems to be URL encoded. Here is how it looks like

`%7B%22Version%22%3A%222012-10-17%22%2C%22Statement%22%3A%5B%7B%22Effect%22%3A%22Allow%22%2C%22Principal%22%3A%7B%22AWS%22%3A%22arn%3Aaws%3Aiam%3A%3A123456789%3Aroot%22%7D%2C%22Action%22%3A%22sts%3AAssumeRole%22%7D%5D%7D`

This is an issue for me because in a different stack, i need to be able to read this json from SSM param store and use it

### Expected Behavior

When the stack is deployed, i expect the following value to be present in the SSM Param store for the key /path/to/parameter

```json
{"Version":"2012-10-17","Statement":[{"Effect":"Allow","Principal":{"AWS":"arn:aws:iam::123456789:root"},"Action":"sts:AssumeRole"}]}

```

### Current Behavior

When the stack is deployed, i noticed that the value in SSM Param store for the key /path/to/parameter seems to be URL encoded. Here is how it looks like

`%7B%22Version%22%3A%222012-10-17%22%2C%22Statement%22%3A%5B%7B%22Effect%22%3A%22Allow%22%2C%22Principal%22%3A%7B%22AWS%22%3A%22arn%3Aaws%3Aiam%3A%3A123456789%3Aroot%22%7D%2C%22Action%22%3A%22sts%3AAssumeRole%22%7D%5D%7D`

### Reproduction Steps

you can deploy the stack, as you would normally after having updated the role for which you are querying the information for

### Possible Solution

_No response_

### Additional Information/Context

I tried decoding the value from the response before storing SSM Parameter store like this

```
new StringParameter(this, "Parameter", {
parameterName: "/path/to/parameter",
description: "Description for your parameter",
stringValue: decodeURIComponent(getRoleCustomResource.getResponseField("Role.AssumeRolePolicyDocument")),
});
```

But this did not work for me

### CDK CLI Version

2.55.0

### Framework Version

2.55.0

### Node.js Version

v18.11.0

### OS

Mac

### Language

Typescript

### Language Version

_No response_

### Other information

_No response_

Start by reproducing the deployment with AwsCustomResource.getResponseField("Role.AssumeRolePolicyDocument") and StringParameter, then inspect how the IAM getRole response is passed into the parameter. Compare the stored value with the expected JSON and trace where URL encoding is introduced; done means the response field is stored in SSM in the expected form without breaking other response fields.

Written by the indexing model from the issue text.