Let sendSms() name the esm_class messaging mode (#92)

* Regression tests for the messaging mode on sendSms()

* Let sendSms() name the esm_class messaging mode

* Document the messaging mode option and the decision behind it

* Name the constants move for migrating consumers and share the refusal's value naming

* Cover the messaging-mode refusals through submitSms()

* Refuse transaction mode and a report under datagram mode on sendSms()

* Narrow the mode checker and name the default mode once

src/index.ts

@@ -61,7 +61,7 @@ export type {
 	SessionOptions,
 } from './session.ts';
 export type { CommandName, PduParams, PduParamsInput } from './defs/commands.ts';
-export type { ConstGroup, MessageState } from './defs/constants.ts';
+export type { ConstGroup, MessageState, SubmitMessagingMode } from './defs/constants.ts';
 export type { Encoding, EncodingName } from './defs/encodings.ts';
 export type { ErrorName } from './defs/errors.ts';
 export type { PduObject, PduObjectInput, TlvInput } from './pdu.ts';