RandomAccessCallback.Wrapper: support multiple state machine instances at same...

RandomAccessCallback.Wrapper: support multiple state machine instances at same time (bitfireAT/davx5#428)

* RandomAccessCallback.Wrapper: support multiple state machine instances at same time

- support multiple state machine instances at same time
- provide explicit Exception/error code when the remote server doesn't support ranged requests

* Only use RandomAccessCallback when server explicitly advertises range requests

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Co-authored-by: Arnau Mora <arnyminerz@proton.me>