Fix volatile eth_gasPrice

[jewei1997]

Describe your changes and provide context

Our current eth_gasPrice uses the reward of the 50th percentile tx in the latest block as part of the calculation. This works decently well if the previous block is congested. However, if the previous block had only 1 tx where the user dramatically overpriced their tx, it will return a very high reward. This often causes our eth_gasPrice endpoint to jump around erratically.

This change uses the previous block's total gas used to determine if the block is congested. If the previous block is congested, we will use the previous logic of 50% of reward. Otherwise, eth_gasPrice now pulls the latest base fee and increases it by 10% to ensure the user's tx can be included in a timely manner without dramatically overpaying.

This also makes a similar adjustment to eth_maxPriorityFeePerGas where if the chain is not congested, a default priority fee of 1gwei is returned to the user.

Testing performed to validate your change

existing unit testing + manually patched it onto an RPC node.

[codecov]

Codecov Report

Attention: Patch coverage is 67.30769% with 17 lines in your changes missing coverage. Please review.

Project coverage is 61.34%. Comparing base (2dc5cc9) to head (6a39936).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
evmrpc/info.go	67.30%	11 Missing and 6 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2006      +/-   ##
==========================================
- Coverage   61.36%   61.34%   -0.02%     
==========================================
  Files         263      263              
  Lines       24483    24525      +42     
==========================================
+ Hits        15024    15045      +21     
- Misses       8341     8358      +17     
- Partials     1118     1122       +4     

Files with missing lines	Coverage Δ
evmrpc/info.go	71.01% <67.30%> (-1.11%)	⬇️

... and 1 file with indirect coverage changes

[codchen]

best to check if receipt.BlockHeight matches height in block, and ignore if mismatch