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.

• context in slack

[MitchTurner]

@Dentosal is this still needed?

We can see where the code posts the blobs:

fuel-core/crates/services/shared-sequencer/src/lib.rs

Lines 134 to 156 in a6e4f34

	pub async fn send<S: Signer>(
	&self,
	signer: &S,
	account: AccountMetadata,
	order: u64,
	blob: Vec<u8>,
	) -> anyhow::Result<()> {
	let latest_height = self.latest_block_height().await?;
	self.send_raw(
	// We don't want our transactions to be stay in the mempool for a long time,
	// so we set the timeout height to be 64 blocks ahead of the latest block height.
	// The 64 is an arbitrary number.
	latest_height.saturating_add(64),
	signer,
	account,
	order,
	self.topic,
	Bytes::from(blob),
	)
	.await
	}

But are we querying for the block height anywhere?

[Dentosal]

Yep already done