* Add nph check to fluffy CI lint
* Add a section on nph usage in the fluffy.guide
* Update copyright years for altered files
* Avoid chained methods formatting style in db code
* Update nph in CI to v0.5
* Remove leftover commented import
* Move comment to avoid nph turning complex list into simple list (nph bug)
* Update nph in CI to v0.5.1
* Formatting fluffy with nph v0.5.1
* Move BlockHeaderWithProof content to content key selector 0
- Remove as content type with content key selector 4
- Replace regular block header with BlockHeaderWithProof at
content key selector 0
* Apply blockHeader content key also to bridge
* Add tests for header with proof generation and verification
- Let accumulator finish its last pre merge epoch (hash_tree_root
on incomplete epoch).
- Adjust code to use isPreMerge and remove isCurrentEpoch
- Split up tests to a set that runs with a mainnet merge block
number and a set that runs with a testing value.