aws_stepfunctions: JsonPath.MathAdd does not accept expressions as parameters

### Describe the bug

JsonPath.MathAdd does not accept expressions as parameters. It runs well with JsonPath.numberAt, but fails when more complex Inartistic Function expression is used. Example: last element of exploded string:
```
parameters={
"Bucket": "my-target-bucket",
"Key": _sfn.JsonPath.format(
"year={}/month={}/{}",
_sfn.JsonPath.string_at("$.Year"),
_sfn.JsonPath.string_at("$.Month"),
_sfn.JsonPath.array_get_item(
_sfn.JsonPath.string_split(
_sfn.JsonPath.string_at("$.SomeBranch.Contents[0].Key"),
"/"
),
_sfn.JsonPath.number_at(
_sfn.JsonPath.math_add(
_sfn.JsonPath.number_at(
_sfn.JsonPath.array_length(
_sfn.JsonPath.string_split(
_sfn.JsonPath.string_at("$.SomeBranch.Contents[0].Key"),
"/"
)
),
),
-1
)
)
)
),
"CopySource": _sfn.JsonPath.format(
f"{parent.config.s3['LandingZone']['Bucket'].bucket_name}/{{}}",
_sfn.JsonPath.string_at("$.SomeBranch.Contents[0].Key")
)
},
```

### Expected Behavior

This should be rendered as:
```
"Parameters": {
"Bucket": "my-target-bucket",
"Key.$": "States.ArrayGetItem(States.StringSplit($.SomeBranch.Contents[0].Key, '/'), States.MathAdd(States.ArrayLength(States.StringSplit($.SomeBranch.Contents[0].Key, '/')), -1))",
"Len.$": "States.MathAdd(States.ArrayLength(States.StringSplit($.SomeBranch.Contents[0].Key, '/')), -1)",
"CopySource.$": "States.Format('my-source-bucket/{}', $.SomeBranch.Contents[0].Key)"
}
```

### Current Behavior

Runtime error:
```
RuntimeError: Error: JSON path values must be exactly '$', '$$', start with '$.', start with '$$.', start with '$[', or start with an intrinsic function: States.Array, States.ArrayPartition, States.ArrayContains, States.ArrayRange, States.ArrayGetItem, States.ArrayLength, States.ArrayUnique, States.Base64Encode, States.Base64Decode, States.Hash, States.JsonMerge, States.StringToJson, States.JsonToString, States.MathRandom, States.MathAdd, States.StringSplit, States.UUID, or States.Format. Received: ${Token[States.ArrayLength.States.StringSplit...LandingZonePartitionObjects.Contents.0..Key........635]}
```

This points, that tokens are not accepted on the input. Only JsonPaths

### Reproduction Steps

Create simple State Machine in Python

### Possible Solution

Allow tokens

### Additional Information/Context

_No response_

### CDK CLI Version

2.64.0 (build fb67c77)

### Framework Version

_No response_

### Node.js Version

v18.12.1

### OS

OS X 13.2

### Language

Python

### Language Version

Python 3.9.6

### Other information

_No response_

Start at the JsonPath.math_add entry point and trace how its arguments are rendered when nested in the reported Python State Machine expression. Reproduce the example with CDK CLI 2.64.0 and compare the generated Parameters to the expected States.MathAdd, States.ArrayLength, and related intrinsic expressions.

Written by the indexing model from the issue text.