[API Implementation]: Expose CookieException constructors

[deeprobin]

This PR implements and fixes #95965.

• Expose constructors
• Add doc comments
• Add new public API to ref assembly
• Add tests for passing null and non-null parameters to the ctors

Potentially breaking change if somebody does reflection hacks:

• Rename the previous internal parameter inner to innerException as defined in the approved API scheme.

Added APIs

namespace System.Net;

public partial class CookieException
{
    public CookieException(string? message);
    public CookieException(string? message, Exception? innerException);
 }

[dotnet-issue-labeler]

Note regarding the new-api-needs-documentation label:

This serves as a reminder for when your PR is modifying a ref *.cs file and adding/modifying public APIs, please make sure the API implementation in the src *.cs file is documented with triple slash comments, so the PR reviewers can sign off that change.

[dotnet-issue-labeler]

Note regarding the new-api-needs-documentation label:

This serves as a reminder for when your PR is modifying a ref *.cs file and adding/modifying public APIs, please make sure the API implementation in the src *.cs file is documented with triple slash comments, so the PR reviewers can sign off that change.

[MihaZupan]

Thanks