Add User Thumbnail Upload

[Threpio]

Required for: https://github.com/hashicorp/terraform-provider-azuread/issues/1012

Do I need to add a different logo than the one that is used for Applications thumbnails? No I will be the application.

[manicminer]

@Threpio Could you take a look at the test failure?

[Threpio]

This error is bizarre - The documentation for this endpoint is duplicated between /user/{id}/thumbnailPhoto and /user/{id}/photo/$value - I will change it to use the second endpoint as that is more in line with the docs.

HOWEVER - In doing so:

https://github.com/manicminer/hamilton/blob/6b5e7f6ac1345d94d93fa890f325ae780ca6b4d2/msgraph/client.go#L448

This will need to change as the content-type header needs to be able to be set to an image format. I don't know how to determine what this will break?

[manicminer]

(Test failures unrelated)