Harvesting: Automatically detect that account is harvesting

[cryptoBeliever]

Current behavior

At this moment mobile wallet will not detect automatically that the account is harvesting if we don't have information about harvesting node in the application.

Expected behavior

The mobile wallet should automatically detect harvesting status:

• using the node key link for the account saved on the blockchain. We can use the statistics service /nodes/nodePublicKey/<key> to find the node. Next we can check if account is harvesting there using /node/unlockedaccount endpoint
• using account public key to check if user is not running node on this account. Can be done also using statistics service and endpoint /nodes/<key>. Next, we can check if an account is harvesting using /node/unlockedaccount endpoint