Unable to set stackId when testing with cfn invoke

When doing local testing of RESOURCEs, `cfn invoke` does not provide the ability to set a `stackId` on the request. This causes any handlers relying on the `stackId` to fail or incorporate special handling for missing `stackId` values.

Ideally, should be able to pass JSON like:
```json
{
"stackId": "test-stack",
"desiredResourceState": {
"Key1": "Value1",
"Key2": "Value2"
},
"previousResourceState": {},
"logicalResourceIdentifier": "SomeIdentifier"
}
```