Arbitrary read access and crash from GetDataSubarrays

This issue is related to #104 (closed). By setting the starting index (or indices) in the GetDataSubarrays-protocol to a negative value we can read values that are located ahead of the array data. Setting the starting index to a sufficiently large negative value also crashes the server. See demo_bug_subarray_2.py for an example script (see lines 720 and out for the bug). We use the Docker compose script in compose.yaml, with Python 3.11.6 and requirements found in requirements.txt.

This is in the latest published version of the open-etp-server ([2023-12-21 14:00:41.345] Info: ReservoirDDMS - OSDU Reservoir DDMS ETP-1.2 Server 1.0 - 102b195a371376a1b11ac292d23b932533276749 (Wed Dec 20 19:49:21 2023 +0000)).