Add OPC UA interface, device, init, and states

[esmith1729]

Initial commit and skeletal structure of files needed for OPC UA lewis emulator.

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To fix the issue, we need to either:

1. Rename the variable to indicate that it is intentionally unused (e.g., _unused_framework_version), or
2. Remove the assignment entirely if it is not needed.

Since there is no indication that the variable is intentionally unused or required for documentation purposes, the best approach is to remove the assignment entirely. This ensures the code remains clean and avoids confusion about the purpose of the variable.

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To fix the problem, we will remove the unused import statement from lewis.core.statemachine import State on line 4. This will eliminate the unnecessary dependency and improve code readability. No other changes are required, as the removal of this import does not affect the functionality of the code.

To fix the problem, we will remove the unused import statement from .states import DefaultState from the file lewis_emulators/opcua/device.py. This will clean up the code and eliminate the unnecessary dependency.

To fix the issue, the unused import statement from lewis.adapters import opcua on line 1 should be removed. This will eliminate the unnecessary dependency and improve the clarity of the code. No other changes are required, as the removal of this import does not affect the functionality of the program.

[esmith1729]

simple_test contains the python OPC server basic emulator from this tutorial: https://opcua-asyncio.readthedocs.io/en/latest/usage/get-started/minimal-server.html
It's recommended to use this format, in conjuction with a python script that opens a port and listens to the traffic between this server and the client (OPCUA IOC), in order to have the same functionality needed for unit tests of our OPCUA IOC.

The goal is to have format similar to the mezei_flipper emulator.