Indexing parameters support

[ashish-spext]

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Describe the feature

Currently index agent just takes index_type (spoken_words or scene) and uses VideoDB's default parameters to index the given video.

In spoken word index: optional language_code param should be supported.

In scene index: extraction_type, extraction_config, prompt and name params should be supported initially.
Later when we introduce scene collection agent we can enable the scenes param as well.

Additional Context

This index agent can be broken into specific index agents as well.

Pro: This approach removes complexity of params and conditional logic inside a single indexing agent.
Con: This approach results in repetition of the boiler plate across index agents.