Make use of PJRT_HostBufferSemantics to avoid unnecessarily copying host buffers

[mrakitaTT]

With change #220 we are fixing host buffer ownership issues by always creating copy of the host buffer. We can avoid doing so depending on the PJRT_HostBufferSemantics given to us by PJRT API caller. For example when semantic is PJRT_HostBufferSemantics_kImmutableUntilTransferCompletes we can just use the given host buffer and call done_with_host_buffer.ready() after executing in runtime.