Dynamically adjust start_block_number for XRPL Indexer to Prevent Indexing error due to online_delete

[ingenlabsltd]

• Use latest block from xrplcluster.com
• Only override start_block_number by checking the difference of upper and lower local node block by certain threshold. (300000 blocks)
• Allow force override and configurable threshold

[ingenlabsltd]

Just gonna open this pull request in here.. Sometimes if I do xrpl verifier restart and the block isn't available anymore at the local node due to online_delete I manually need to adjust the start_block_number to prevent indexing error. This patch fixes it dynamically with certain block difference threshold to force use the latest start block number.

-- The script assumes that you have already synced the node atleast 14 days of data and probably atleast 14 days of indexed data for it to trigger the update_start_block_number