Add dencun eth_blobBaseFee and eth_feeHistory changes

[ryanschneider]

Rationale

These RPC changes were agree on in ethereum/execution-apis#486, a common use case is for L2s that are trying to integrate with blobs need access to these methods.

In summary, there are two changes:

• Add eth_blobBaseFee which returns the expected base fee for blobs in the next block.
• Add two new blob-related fields to eth_feeHistory: baseFeePerBlobGas and blobGasUsedRatio

Implementation

I'll try to get a PR up to implement these this afternoon, I did scan and didn't see anything in flight anywhere but am happy to defer if someone else is already working on this.