Refactor Upload Task

[ramsessanchez]

Refactor the Upload Task in GraphCore to make use of the newly created ClientFactory.

[maisarissi]

As part of this work, we should also remove the slice size constraint.
The SDK must have a default value of 5MB but it shouldn't throw an exception when the slice size isn't multiple of 320KiB.
The max slice size parameter should be optional, so users can change the slice size to allow other scenarios.

Please refer to microsoftgraph/msgraph-sdk-dotnet-core#475 for context.