Add Rewards data to rosetta-java

[Kammerlo]

Currently in rosetta-java it is not possible to query pending rewards from a stake address.
The balance is currently calculated by the utxo. Since it is possible now to query the rewards from a stake address, it must be included in rosetta.

Currently we are returning the UTxOs owned by the stakeaddress, which is basically wrong in this case. A user expects the pending rewards to be returned, when querying the stakeaddress.

Places to change it:

• AccountServiceImpl.java
• Yaci-indexer - Add Rewards quering (an example how to do it Yaci-Store AccountService
  The n2c communication between yaci-store and the node is already setup.

Think of a way how to get the data from yaci-store to the API.
Probably the best way would be via an http, since we need the response synchronously.
Possible ways could be establish an http connection or do it via the database.