fix(assistantState): cache full state when reloading assistant

[waziers]

• Add examples dependency to submit handler (last state loaded)
• Center data-load spinner and wrap both UIs

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[gtricerriv]

Changes are only a proof of concept, for context the nested useCallback in the assistant UI is being cached before all data is received on hard page reload (redux state wipe). I tried adding a wrapper that waits till everything is fetched but it seems transpiled code is still generating a submit handler whose actual dependencies are incomplete at the time of caching.

I will update it based on any feedback so that it adheres to the contributing guidelines.