Minimal node blockchain sync

[dmugtasimov]

DEPENDS ON:

• Do not rename chunk file on each block #297
• Implement APIBlockchain.yield_blocks_slice() #387

TODO:

• [DONE] Implement sync_minimal(source_blockchain: BlockchainBase, target_blockchain: BlockchainBase) function
• Implement APIBlockchain -> partially moved out Implement APIBlockchain.yield_blocks_slice() #387
• [DONE] If we do not have the latest blockchain state then get it
• [DONE] Drop previous blockchain states to avoid gaps (this will be changed back with Fill gaps sync #290 )
• [DONE] Download all blocks remained after latest blockchain state
• Deal with convergence issue (where blockchain gets more blocks and blockchain states while we are syncing - which may require resync indefinitely)
• Another issue to deal with is that different nodes may have different number of blocks in their blockchain
• Yet another issue is that PV will probably be most up to date node always
• [DONE] Enable caching after changing the way we put blocks in chunks -> do not put blocks to chunks until finalized -> Do not rename chunk file on each block #297

[dmugtasimov]

Return metadata: #293

[dmugtasimov]

#346

[dmugtasimov]

#377

[dmugtasimov]

#379

[dmugtasimov]

#382

[dmugtasimov]

#385

[dmugtasimov]

#386

[dmugtasimov]

Returning blockchain states does not seem to work correctly. Fix it first and then move forward with the task.

[dmugtasimov]

#407

[dmugtasimov]

#408

[dmugtasimov]

#409

[dmugtasimov]

#410

[dmugtasimov]

#411