[sam2][frame-loading] Add streaming frame loading on top of lazy loading

[sentfb]

The AsyncVideoFrameLoader expects image paths to be available ahead of time but loads frames lazily. The Streaming loader does not assume that all inputs are available ahead of time but still loads frames lazily.

Refactored AsyncVideoFrameLoader into a LazyVideoFrameLoader class and extended 2 implementations that are: 1) lazy input + lazy load and 2) eager input + lazy load

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[sentfb]

@raedle, @ronghanghu PTAL and also advise how I can run CI tests for this PR.

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