Disallow argument mismatch between interface and implementation

[iliapolo]

Currently, the compiler will allow the following program:

export interface IAdder {
  add(a: number, b: number): number;
}

export class Adder implements IAdder {
  public add(a1: number, b1: number): number {
    return a1 + b1;
  }
}

Notice the argument names in Adder.add are different from IAdder.add.

This results in an incompatibility between the IAdder interface and the Adder class in python. See:

• (aws-rds): "DatabaseSecret" is incompatible with protocol "ISecret" aws-cdk#27852
• (@aws_cdk): Python: incompatible interface implementations due to differing function argument names jsii#4541
• (IAM): Role incorrectly implements interface IRole (Python) aws-cdk#21099
• (ec2): Subnet and ISubnet variable naming causes Pylance type error aws-cdk#20125

We should have the compiler enforce that functions in implementations (or subclasses) use the same argument names as the parent.

Notes

• Unless we roll out a new major version, we cannot start enforcing this on existing projects because the fix would have to be argument renaming, and this would be a breaking change. In order to maintain backwards compatibility and stop the proliferation of this mistake, we need to provide an allow list mechanism to ignore existing violations, as well as a feature toggle to activate this validation. In the next major version of the compiler, we can remove these provisions and start enforcing it.
• It would be nice to resurrect and merge fix(jsii-diff): renaming a positional argument is a breaking change in Python jsii#2937 as well, as this would protect us against accidental renaming, either in an attempt to fix the inconsistency, or just an ad-hoc decision to rename some arguments.

[iliapolo]

We should only pick this up after a decision has been made with respect to aws/jsii#4541 (comment)