aws_cdk.cloudformation_include: CfnInclude overwrites nested stack tags

### Describe the bug

We have a CloudFormation template that defines a nested stack (AWS::CloudFormation::Stack). The template defines a few stack tags via the `Tags` section. When including this template via `aws_cdk.cloudformation_include.CfnInclude`, it overwrites these tags with the ones that are coming via `aws_cdk.Tags` in code.

### Expected Behavior

The tag lists should be merged together.

### Current Behavior

It tried to delete the tags defined in the template, as shown by `cdk diff`.

### Reproduction Steps

Define a CloudFormation template with a nested stack that has `Tags` defined. Then include that template in CDK via `aws_cdk.cloudformation_include.CfnInclude`. Set additional tags on the stack via `aws_cdk.Tags.of`. Then deploy. Observe that the nested stack is missing the tags from the template.

### Possible Solution

_No response_

### Additional Information/Context

_No response_

### CDK CLI Version

2.28.0 (build ba233f0)

### Framework Version

_No response_

### Node.js Version

v16.15.1

### OS

Alpine 3.16

### Language

Python

### Language Version

3.10.5

### Other information

_No response_

Start at aws_cdk.cloudformation_include.CfnInclude and reproduce the nested AWS::CloudFormation::Stack case with template Tags plus tags applied through aws_cdk.Tags.of. Use cdk diff to inspect the generated tag changes; done means template tags are retained and additional CDK tags are merged rather than overwritten.

Written by the indexing model from the issue text.