This PR improves the endpoint functions to not generate body & parameter arguments for APIs that don't need them. This reduces type clutter a little, and avoids generating impossible signatures.

For instance, POST /me/reprocessLicenseAssignment was generated with this effective signature:
function create(body: never, params?: {} | undefined) : whatever

This API doesn't take any body or params at all, so the types.ts requestBody type for this API is 'never'. Our code has assumed that all non-get, non-delete APIs will always require a body however, so we've been happily generating the body argument. The result is that body: never argument - which is problematic as there's nothing I can pass to satisfy it.

The empty params type is not problematic as such, but it's a bit of clutter.

To make this PR reviewable, I only re-generated a handful of endpoints to show the difference before/after the changes. and keep the PR readable I'm planning to re-generate everything next week and that'll propagate the fixes.

Other minor things

• paramDefs are made optional in the EndpointRequest type, to match params and reduce clutter
• the EndpointRequest and CallOptions types are exported out of the Graph client, to make it easier to make custom endpoint functions.
• the graph-endpoints and graph-endpoints-beta readmes are updated to correct links & instructions.