[EVM] subscribe logs empty params crash

[jewei1997]

Describe your changes and provide context

Our websocket RPC would crash when given this empty filter where we don't filter on anything so it should return all logs: {"jsonrpc":"2.0","id": 2, "method": "eth_subscribe", "params": ["logs"]}. This PR creates an empty filter if the filter given as input from the rpc is nil.

Testing performed to validate your change

unit tests, manual testing locally.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.51%. Comparing base (aefdcf8) to head (58ed215).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1779      +/-   ##
==========================================
+ Coverage   61.47%   61.51%   +0.04%     
==========================================
  Files         257      257              
  Lines       22284    22287       +3     
==========================================
+ Hits        13698    13710      +12     
+ Misses       7629     7619      -10     
- Partials      957      958       +1     

Files	Coverage Δ
evmrpc/subscribe.go	66.83% <100.00%> (+2.10%)	⬆️

... and 2 files with indirect coverage changes