Add block height support in rpc call getblock

[salisbury-espinosa]

feature request: RPC getblock accepts height or hash
in the upstream there are 2 unaccepted PR:
https://github.com/bitcoin/bitcoin/pull/8457/files
and duplicate https://github.com/bitcoin/bitcoin/pull/14858/files
Rejection argument: bitcoin#8457 (comment)
Is there a place for these changes in dash?

[UdjinM6]

This could be helpful probably but I agree with reasons provided for not merging it, at least for an overloaded version. If anything I would rather see smth like this implemented as a separate rpc (e.g. getblockbyheight as suggested in one of the comments) which would clearly state in its help text that this rpc returns a block in best-block-chain at height provided (as in getblockhash) meaning that results can change if there is a reorg later.

[dashuser33]

As someone working with the RPC, plus one on not overloading existing commands. A new command is way better.

[PastaPastaPasta]

btw: there is an implementation here bitcoin#16345 of this