v0.19.0 - Merge target and auth changes

[jchancellor-ms]

Description

This PR is intended to be the last signficant release prior to going v1. It contains a number of deprecations and potentially breaking changes.

1. This will be a merge target for previously submitted PR's so that they can be tested and merged.
2. Merged PR's will include moving functionality to sub-modules from direct resources in the module.
3. This PR contains a complete refactor of the authentication interfaces. It consolidates a number of auth related variables into a single interface to minimize authentication misconfiguration related issues.
4. It removes some older deprecation interfaces
5. It will update the examples to reflect the new authentication and sub-module changes
6. It will also extend functionality for ordering extensions to 5 ordered extensions.
7. It will add the ability to order network interfaces to address a long-running issue for interface ordering.

Type of Change

• Non-module change (e.g. CI/CD, documentation, etc.)
• Azure Verified Module updates:
  • Bugfix containing backwards compatible bug fixes
    • Someone has opened a bug report issue, and I have included "Closes #{bug_report_issue_number}" in the PR description.
    • The bug was found by the module author, and no one has opened an issue to report it yet.
  • Feature update backwards compatible feature updates.
  • Breaking changes.
  • Update to documentation

Checklist

• I'm sure there are no other open Pull Requests for the same update/change
• My corresponding pipelines / checks run clean and green without any errors or warnings
• I did run all pre-commit checks

[donovm4]

approving