Add support for batching

[baywet]

Similar to microsoftgraph/msgraph-sdk-go-core#11
Checkout for reusable code https://github.com/microsoftgraph/msgraph-sdk-javascript

[filipvh]

I seem to not get this to work. I'm also finding it hard to find a good example. When i do get it to work, the bodies seem to be empty.
https://github.com/microsoftgraph/msgraph-sdk-typescript-core/blob/main/src/content/BatchRequestStep.ts#L160
this seems to fail because the body is an object and not a string.