Refactor muxing 1 : Re-use same config to configure the SDK and PF providers, fix VCR testing

[modular-magician]

Fixes hashicorp/terraform-provider-google#19197
Fixes hashicorp/terraform-provider-google#18774
Fixes hashicorp/terraform-provider-google#20280

Summary

This PR:

• Changes how the plugin-framework implementation of the provider is configured
  • Before: Parallel implementation of configuration logic that parses user inputs and populates a fwtransport.FrameworkProviderConfig struct
  • After: The configure function obtains an already populated transport_tpg.Config struct from the SDK provider, with no duplication of logic to process user inputs.
• Changes code defining the VCR system to accommodate the change above
  • Now the PF provider uses the same Config struct as the SDK provider, both providers can use the same cached configs.
  • This fixes VCR test(s) fail during replay: Framework converted resources hashicorp/terraform-provider-google#14158 , because a single test will use a single cached client again.
• Makes necessary changes to the data sources currently implemented with the plugin-framework
  • These now expect to receive a transport_tpg.Config struct
  • Any provider-level values are now in the old type system, and require thought about where we convert between those type systems.

Things to pay attention to during review/testing

• What acceptance tests need to be updated now that the PF provider is configured in a SDK-like way?
• Are only changes just to the test required, or do the failures indicate user-facing changes in behaviour?
• Tests
  • 🔴 Acceptance tests for the provider's configuration behaviour are mostly VCR skipped. Testing this PR will require use of TeamCity!
  • Manual testing encouraged
  • We should look at known bugs linked to the muxing and confirm they're gone before merge
    • data.google_dns_managed_zone always fails with "Post "https://oauth2.googleapis.com/token": context canceled" hashicorp/terraform-provider-google#16832 (comment)
  • After merge, we should closely monitor nightly tests and not rely on the Release Shepherd picking up any failures linked to this PR. Newer tests will provide more signal.

---

provider: refactored how the provider configuration is handled internally

Derived from GoogleCloudPlatform/magic-modules#11903

[conventional-commit-lint-gcf]

🤖 I detect that the PR title and the commit message differ and there's only one commit. To use the PR title for the commit history, you can use Github's automerge feature with squashing, or use automerge label. Good luck human!

-- conventional-commit-lint bot
https://conventionalcommits.org/