Interactivity API Docs: Add initial version of getContext and getElement

[cbravobernal]

What?

Add getElement and getContext functions to the API Reference in Interactivity API.

Why?

Those functions will be widely used. In special getContext(). Should be added to the dev note and be referenced in the docs.

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Co-authored-by: c4rl0sbr4v0 <[email protected]>
Co-authored-by: fabiankaegy <[email protected]>

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