feat(db): Allow maxValueSize as option

[Schartey]

The maximum allowed value size was hardcoded to 1mb.
To allow storing bigger values I added the option MaxValueSize that can be set on badger initialization.

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This change is 

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[poonai]

@Schartey Thanks for the contribution.

Please sign the contributor agreement for us to merge the PR.

[manishrjain]

I think would be good to have a test which writes large values and is able to retrieve them fine, after having closed the DB and re-opened it.

Reviewable status: 0 of 2 files reviewed, all discussions resolved (waiting on @jarifibrahim)