Implement new API to the explorer and disable RPC

[selankon]

Here some tasks that need to be finished before we can disable old RPC from the backend.

Pending API implementation

@jordipainan @p4u

• Transactions on a block Add endpoint to get transactions references of a specific block #57
• Transactions paginated list (we can do a Promise.all like with the blocks)

Pending to merge or be deployed on dev

@jordipainan

• List of blocks (currently pending merge, this one does a Promise.all of blocks by height Implement block list by height explorer-ui#127, it has a blocker) Related: /chain/blocks : list of blocks. Currently it could be solved making successive calls to /chain/blocks/{height}, but will be better for the client to simply retrieve a list of blocks, as dvote did #33 . Blocked by following PR
• Transaction info -> Get tx details using the sdk explorer-ui#119 Blocker -> Add Tx info when get tx by height #40
• Block details -> Use Vocdoni sdk for block detail explorer-ui#115 Blocker -> Return blockHash on a block info response #36
• Organizations list + filters F/vocdoni sdk organizations list explorer-ui#130 Blocker -> Filtered organization list not return electionCount #63

Pending explorer implementation

@selankon

• Process list + filters F/vocdoni sdk organizations list explorer-ui#130
• Election list + filters Migrate some elections RPC hooks to SDK  explorer-ui#131
• Replace the useProcessKeys hook (I imagine it's a hook that retrieves the decryption keys of an encrypted election, now they come with the election info)
• Entity metadata (check where is using import { useEntity } from '@vocdoni/react-hooks')
• Organization details page Migrate organization details to SDK  explorer-ui#133

Final changes

The only remaining PR to merge that will deprecate the RPC is this:

• Deprecate last RPC dependencies explorer-ui#138

It already has some pending issues that need to be merged on vocdoni node.

• Implement block to date method #68
• Add endpoint to get transactions references of a specific block #57

[p4u]

@selankon issue #407 does not exist