[GSK-3652] Add set embedding model (for OpenAI client)

[henchaves]

Description

Related Issue

Type of Change

• 📚 Examples / docs / tutorials / dependencies update
• 🔧 Bug fix (non-breaking change which fixes an issue)
• 🥂 Improvement (non-breaking change which improves an existing feature)
• 🚀 New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to change)
• 🔐 Security fix

Checklist

• I've read the CODE_OF_CONDUCT.md document.
• I've read the CONTRIBUTING.md guide.
• I've written tests for all new methods and classes that I created.
• I've written the docstring in Google format for all the methods and classes that I used.
• I've updated the pdm.lock running pdm update-lock (only applicable when pyproject.toml has been
  modified)

[linear]

GSK-3652 Add `set_embedding_model` method

[sentry]

🔍 Existing Issues For Review

Your pull request is modifying functions with the following pre-existing issues:

📄 File: giskard/llm/embeddings/openai.py

Function	Unhandled Issue
try_get_openai_embeddings	OpenAIError: The api_key client option must be set either by passing api_key to the client or by setting the O... ... Event Count: 7
try_get_openai_embeddings	OpenAIError: The api_key client option must be set either by passing api_key to the client or by setting the O... bs.rag... Event Count: 4

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[sonarqubecloud]

Quality Gate failed

Failed conditions
50.0% Coverage on New Code (required ≥ 70%)

See analysis details on SonarCloud

[sonarqubecloud]

Quality Gate failed

Failed conditions
50.0% Coverage on New Code (required ≥ 70%)

See analysis details on SonarCloud