Update TeamCity diff checker tool

[modular-magician]

Description

This PR:

• Adds testing to the TC diff checker
• Refactors logic to add more user feedback and provide feedback about mismatches in both directions between TC config and provider code
• Changes how the tool is invoked from GHAs

Context

TeamCity diff checker has been failing for a few weeks:

Here is an example:

This error is confusing because:

• services_ga.kt only contains recaptchaenterprise, not recaptcha
• The GA provider contains only a services/recaptchaenterprise package, and there isn't a services/recaptcha.

However:

• There is a services/recaptcha in the Beta provider
• This is missing in the services_beta.kt file
  

With better user feedback this could be less confusing

Derived from GoogleCloudPlatform/magic-modules#12426