Fix incorrect links for operation input / output members in docgen

[joewyz]

Background

Current Smithy Docgen generated incorrect links for operation input / output members.
For example:

@paginated(inputToken: "nextToken", outputToken: "nextToken", pageSize: "pageSize", items: "items")
operation PaginatedOperation {
    input := {
        nextToken: String
    
        pageSize: Integer
    }

    output := {
        items: Items

        nextToken: String
    }
}

The generated link for paginated trait's token would be something like:./../shapes/PaginatedOperationInput.md#paginatedoperationinput-nexttoken. This is incorrect because we do not generate separate files for operation input / output structures.

With this fix, Smithy Docgen can produce correct link: ./PaginatedOperation.md#paginatedoperation-nexttoken
This should fix issue #2921

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[JordonPhillips]

They should have a -request-members or -response-members suffix, since those targets are getting generated already. That should probably be shortened to -input and -output but it's not critical.

[joewyz]

Added -request-members and -response-members suffix, it would require more changes in MemberGenerator to align with the shortened suffix

[JordonPhillips]

This is better since we're going to the right page now, but I wonder if the links still work