Align SSL verification options with core for Central commands

[lucadruda]

IoT Central commands don't follow CLI core settings for SSL certificate validation

• Added code to handle "AZURE_CLI_DISABLE_CONNECTION_VERIFICATION" environment variable
• Use of "Session" for request module to share options between requests

---

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact [email protected] with any additional questions or comments.

Thank you for contributing to the IoT extension!

This checklist is used to make sure that common guidelines for a pull request are followed.

General Guidelines

• [ ] If introducing new functionality or modified behavior, are they backed by unit and integration tests?
• [x] In the same context as above are command names and their parameter definitions accurate? Do help docs have sufficient content?
• [x] Have all unit and integration tests passed locally? i.e. pytest <project root> -vv
• [x] Have static checks passed using the .pylintrc and .flake8 rules? Look at the CI scripts for example usage.
• [x] Have you made an entry in HISTORY.rst which concisely explains your feature or change?

[lucadruda]

Change session back to single execution. The verify option is passed to every requests. This helps when testing fine grained. Converting to draft until tests ready.

[digimaun]

Closing due to inactivity.