pass block into the metagraph class

[surcyf123]

Is your feature request related to a problem? Please describe.

I am running a script to compare the weights at different times, and to do this I need to get the metagraph from a previous block. There is currently no way to pass in the block to bt.metagraph(), you first need to load the metagraph for a subnet and then run metagraph.sync( block=desired_block )

Describe the solution you'd like

Add a block parameter to the metagraph class to sync to a desired block without having to load the metagraph first for the current block.

Describe alternatives you've considered

No response

Additional context

block = subtensor.get_current_block()
print("Current block:", block)
meta = bt.metagraph(netuid=23, lite=False)
meta.sync(block=block)  # Sync the metagraph with the current block

# 1200 blocks earlier, or 4 hours
previous_block = block - 1200
meta2 = bt.metagraph(netuid=23, lite=False)
meta2.sync(block=previous_block)  # Sync the metagraph with the previous block

weights = meta.W.tolist()
weights2 = meta2.W.tolist()```