Add method to set body type from Outlook add-in

As of now you can get the body type (HTML or text) of a message from an add-in through the https://docs.microsoft.com/en-us/javascript/api/outlook/office.body?view=outlook-js-1.11#outlook-office-body-gettypeasync-member(1) API.

We would like a Body.setTypeAsync method for changing the body type:

setTypeAsync(coercionType: Office.CoercionTypeOptions, callback?: (asyncResult: Office.AsyncResult<void>) => void): void;