Shared sequencer: fetch and use latest block height

[Dentosal]

Update the shared sequencer service to use the following query to find the block height, and post blobs starting from that height:

curl --request POST   --url https://rpc-seq.simplystaking.xyz/   --header 'Content-Type: application/json'   --data '{"jsonrpc": "2.0","id": 1,"method": "tx_search","params": {"query": "message.action='\''/fuelsequencer.sequencing.v1.MsgPostBlob'\'' AND message.sender='\''fuelsequencer14t0nvrj4v3at8f4fzywfn0qrsu4532ns7n4ywv'\''","prove": true, "order_by": "desc", "page": "1", "per_page": "1"}}'

During the initialization of the service, we need to know what is the latest SS block height where we posted blobs.
If we know it, we can request all blobs from this SS block, parse them, and find the latest posted information which contains the height of the Fuel block.
After we know the latest Fuel height was submitted, we can start submitting new blocks.

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