Add params to nb-tester

[emilkovacev]

Effectively allows the nb-tester script to be run against any backend. Also allows you to pass authentication and configuration directly to QiskitRuntimeService (if preferred).

Here's an example of how you can use the new changes to run a set of notebooks against test_eagle using qiskit_ibm_runtime:

test-docs-notebooks --config-path scripts/config/notebook-testing.toml --provider "qiskit_ibm_runtime" --backend "test_eagle2"

By default, --provider is set to qiskit_fake_provider, which runs the same provider code that was present in nb_tester before. By changing the provider, you can also specify "runtime_fake_provider" to use the fake_providers in qiskit_ibm_runtime.fake_provider, or "qiskit_ibm_runtime" to rely on real backends, and the credentials provided.

This shouldn't require changes in CI yet - it seems like notebook testing CI is able to complete the same number of tests as in main, although it does carry over some errors that I ran into on main too.

[qiskit-bot]

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[emilkovacev]

PR migrated to #2350 to run full CI process