Move pb2 Files to Own Folder

[rc14193]

Motivation and Context

Since the pb2 files are auto generated and shouldn't be manually changed, I think it might be better if they're in their own subfolder. This makes things cleaner and makes it clearer what are the core files of the project.

Description

This is implemented by performing the following:

• Add a mv command to regen-protobufs to transfer files to PbDefinitions subfolder.
• Adding an additional sed command to update imports in the pb2 files.
• Manually updating import calls in other files in the project

Testing

pytest was run on both branches and test results were the same

Pytest on Changes

Pytest on Main

[CLAassistant]

All committers have signed the CLA.