`BlockNotFound` Might Not be Properly Returned When The Underlying Node is Not Reth/Anvil

[0xNeshi]

When a queried block is not found on-chain, the RobustProvider returns (or intends to) BlockNotFound error. This was done to avoid the ambiguity of alloy of just returning None.

The problem is that different Nodes have different behavior when querying for non-existent blocks:

• Anvil (dev node): Returns None
• Reth node: Returns None
• Geth node: Return an RPC error (exact error message to be determined)
• etc.

We need to have tests running on different nodes verifying that the expected behavior is present, i.e. whether alloy properly converts all Nodes' "block not found" particular errors/results into None (and by extension, that RP converts to BlockNotFound).