SKALED-1811 Fix net_version call error

[dimalit]

Unit test jsonrpc_netVersion was failing, not it works.
Root cause: ChainParams was held by reference in class Net, it caused it to point to freed memory. Now it's held by value.

[github-actions]

SUGGESTIONS BEFORE MERGE:

1. Build custom container here: https://github.com/skalenetwork/skaled/actions?query=workflow%3A%22Custom+Docker+and+Binary%22
2. Test it here: https://github.com/skalenetwork/skale-ci-integration_tests/actions?query=workflow%3A%22Skaled+Nightly+Tests%22
3. Edit VERSION file appropriately to your changes!
   See https://skalelabs.atlassian.net/wiki/spaces/SKALE/pages/2444951553/Branching+instructions

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 42.78%. Comparing base (4e5ad12) to head (20dd548).

Additional details and impacted files

@@           Coverage Diff            @@
##           v3.17.2    #1814   +/-   ##
========================================
  Coverage    42.78%   42.78%           
========================================
  Files          392      392           
  Lines        57121    57121           
========================================
  Hits         24439    24439           
  Misses       32682    32682