MessagingServiceSid and statusCallback should be nullable to be consistent with twilio npm module

[ZodsPlan]

Issue Summary

The OAI specification for twilio API seems to be incorrect, or at least the nodejs implementation of twilio api may have an inconsistency. https://github.com/twilio/twilio-oai/blob/main/spec/yaml/twilio_api_v2010.yaml#L17395 - should be nullable to be consistent with the typings for twilio api. the OAI specification requires messagingServiceSid whereas the api does not. The same goes for statusCallback; it should be nullable to be consistent with twilio api.

Steps to Reproduce

1. install latest version of twilio via npm
2. npm install -g prism-cli
3. run prism mock https://github.com/twilio/twilio-oai/blob/main/spec/yaml/twilio_api_v2010.yaml
4. create a custom http client

Code Snippet

import twilio from 'twilio';

class PrismHttpClient extends RequestClient {
    request<TData>(opts: RequestClient.RequestOptions<TData>): Promise<Response<TData>> {
        opts.uri = opts.uri.replace(/^https:\/\/.*?\.twilio\.com/, 'http://127.0.0.1:4010'); // note: default prism port is 4010, so change if needed
        return super.request(opts);
    }
}

Then...

const opts ={httpClient: new PrismHttpClient()};
const client = smsClient(sid, token, opts);
const response = await client.messages
        .create({
            body: text,
            from,
            to,
            statusCallback: 'http://localhost:9000/status' // any url where twilio should post message status - this should be nullable also but it is not according to the twilio oai
        });

Then run that code.

Exception/Log

[5:49:29 PM] ›     [VALIDATOR] ⚠  warning   Request did not pass the validation rules
[5:49:29 PM] ›     [VALIDATOR] ✖  error     Request body property MessagingServiceSid must NOT have fewer than 34 characters
[5:49:29 PM] ›     [VALIDATOR] ✖  error     Request body property MessagingServiceSid must match pattern "^MG[0-9a-fA-F]{32}$"
[5:49:29 PM] › [HTTP SERVER] post /2010-04-01/Accounts/AC6d4932eed0ae3cf5d9af4f071965be8f/Messages.json ✖  error     Request terminated with error: https://stoplight.io/prism/errors#UNPROCESSABLE_ENTITY: Invalid request

Technical details:

• twilio-oai version: latest
• twilio version: 4.11.1
• open version:

[twilio-dx]

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