Add LlamaIndex dependency in SMD

### 🚀 The feature, motivation and pitch

We are planning to use SMD for running inference workflows. LangChain & LlamaIndex are most popular workflow frameworks. SMD already has LangChain dependencies. It would add a lot of value to customer if we support both LangChain & LlamaIndex out of the box in SMD.

### Use case description

_No response_

### Alternatives

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### Additional context

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No file or test is named. Start by finding where SMD’s existing LangChain dependencies are declared and how the Docker images install them. Add LlamaIndex alongside that dependency, then verify the relevant image builds and the package can be imported.

Written by the indexing model from the issue text.