Expose Response Headers in API exception/error [Swift]

[andrueastman]

To improve the error handling experience we need to add the response headers the main api error type:

• add a response headers field to the Api exception class
• add corresponding accessors (if needed)
• populate the information in the request adapter when an error is encountered

Examples
Dotnet

• Adds response headers to APIException kiota-dotnet#79
• Include response headers in API exception kiota-http-dotnet#94

Java

• Adds reponseheaders to API excpetion kiota-java#299

Typescript

• Adds response headers to API error kiota-typescript#617

Go

• Adds response headers to API exception kiota-http-go#81
• Adds response headers to API exception kiota-http-go#81