Fork event manager when creating EVM snapshots

[codchen]

Describe your changes and provide context

Create a new event manager when snapshots are created so that events created in the new snapshot can be cleanly reverted when the snapshot itself is reverted.

Not apphash-breaking because events are not part of consensus

Testing performed to validate your change

unit test

[codecov]

Codecov Report

Attention: Patch coverage is 87.50000% with 1 line in your changes missing coverage. Please review.

Project coverage is 60.98%. Comparing base (e8e4b3b) to head (ac739ff).
Report is 145 commits behind head on main.

Files	Patch %	Lines
x/evm/state/statedb.go	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1831      +/-   ##
==========================================
- Coverage   61.64%   60.98%   -0.67%     
==========================================
  Files         365      257     -108     
  Lines       26178    22565    -3613     
==========================================
- Hits        16138    13761    -2377     
+ Misses       8967     7831    -1136     
+ Partials     1073      973     -100     

Files	Coverage Δ
x/evm/state/state.go	95.45% <100.00%> (ø)
x/evm/state/statedb.go	50.43% <85.71%> (-1.53%)	⬇️

... and 176 files with indirect coverage changes