refactor(readhandler): Group multiple nodes into a single request

[jrtitus]

Improves read performance by grouping resources in commands into a single OPC UA request.

Special thanks to @syoliver for providing a majority of the necessary modifications.

PR Checklist

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Please check if your PR fulfills the following requirements:

• I am not introducing a breaking change (if you are, flag in conventional commit message with BREAKING CHANGE: describing the break)
• I am not introducing a new dependency (add notes below if you are)
• I have added unit tests for the new feature or bug fix (if not, why?)
• I have fully tested (add details below) this the new feature or bug fix (if not, why?)
• I have opened a PR for the related docs change (if not, why?)

Testing Instructions

• Run EdgeX Foundry and device-opcua service as normal

New Dependency Instructions (If applicable)

N/A

[nyameen]

LGTM - Minor change, not totally required.