Harvesting: Join "Key links" and "Persistent delegated message" steps

[cryptoBeliever]

Current behavior

At this moment harvesting in the mobile wallet is working in the following way:

• create account links (remote, VRF, node)
• send a persistent delegated message

Expected behavior

Two steps (key links and persistent delegated message) should be joined. It will simplify the harvesting view.
It's important to put a persistent delegated message in aggregate after key link transactions.

Example transaction:
https://symbol.fyi/transactions/43748B7F9868E624A72F8D81A394C2CBCF1A4021B5DF255501B1B9BAD2D494D6

The wallet should work in the following way:

Start harvesting should send one aggregate transaction containing

• unlink remote account (if an account is already linked and we don't have a private key for it in storage. We should unlink also if the storage remote private key doesn't generate a remote public key that is already linked in the network)
• unlink the VRF key (if an account is already linked and we don't have a private key for it in storage. We should unlink also if the storage VRF private key doesn't generate a VRF public key that is already linked in the network)
• unlink node key (if a node key is linked - we need to unlink the old one)
• link remote account (only if we had to remove the old one - then we have to generate and link a new key)
• link VRF key (only if we had to remove the old one - then we have to generate and link the new key)
• link node key (always)
• persistent delegated message (always)

Stop harvesting should send one aggregate transaction containing:

• unlink node key (only if a node key is linked do we need to unlink the old one)
• unlink remote account (only if an account is already linked and we don't have the private key for it in storage)
• unlink VRF key (only if an account is already linked and we don't have the private key for it in storage)