[Feature] Add block number, network and timestamp to transaction endpoint

[jrchatruc]

🚀 Feature

Modify both the /testnet3/transactions/{height} and /testnet3/transaction/{tx_id} endpoints to return information about the block number the transactions were included in, the network they belong to and the timestamp of the block they were included in.

Motivation

Including this information on the detail of every transaction would improve the Explorer so it has to to do less data manipulation, as currently it has to retrieve it from blocks and to show it.