Implement block list endpoint

[selankon]

This PR implements a block list endpoint on the API: https://github.com/vocdoni/vocdoni-node/pull/1329

This have to be implemented on:

• [ ] Type and export the interface on the SDK and implement the endpoint on the ChainAPI
• [ ] The block details interface have to be updated on the SDK. At least a new attribute is added (txCount) and others may be dissappeared (txs)
• [ ] Implement the method on the Extended SDK
• [ ] Implement the blocklist on the explorer

[altergui]

here's what i have so far:

• GET /chain/blocks
  • page
  • limit
  • chainId
  • hash
  • proposerAddress

chainId and proposerAddress match exactly, hash matches partially (substring)

[altergui]

in the reply, not all blocks listed will have all their fields filled in, since back at the time we only indexed height and timestamp. so the first N blocks will only return height and timestamp, i.e. no hash, chainId nor proposerAddress. also those old blocks won't be included in results when using any of those filters, of course

[altergui]

since that PR will take longer, i cherry-picked and adapted the relevant code to work without the indexer, to not block this interop issue longer https://github.com/vocdoni/vocdoni-node/pull/1369

[altergui]

here's what i have so far:

* GET /chain/blocks

  * page
  * limit
  * chainId
  * hash
  * proposerAddress

chainId and proposerAddress match exactly, hash matches partially (substring)

@marcvelmer this is what i implemented and is merged on backend (the filters don't actually filter yet, but for interop it's irrelevant since the format of the params and the returned reply won't change when that's finished)

https://developer.vocdoni.io/vocdoni-api/list-all-blocks