feat(live-updates): add getCurrentBundle() and getNextBundle() method

[robingenz]

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Close #225

[tbence94]

Could this getNextBundle() call help me decide if there is a newer version before calling sync() to actually download it?
I would like to show some loading/updating screen to the user if there is a bundle being downloaded in the background when running sync.

I couldn't find a way to do this with the current API, because sync is the only option to check for new updates, but it also downloads it immediately.

[robingenz]

@tbence94 No, i guess you are looking for this issue: #263