Add support for custom schain patch timestamps

[dmytrotkk]

This PR added support for custom patch timestamps based on env and sChain name.
Legacy patch timestamp format will remain supported.

Config format example:

schain:
  contractStorageZeroValuePatchTimestamp:
    default: 800000
    test-schain: 1500000
  revertableFSPatchTimestamp: 1000000
  contractStoragePatchTimestamp: 1000000

New tests added to tests/schains/config/static_params_test.py.
No performance changes.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.57%. Comparing base (fbb2fb0) to head (002f607).

Additional details and impacted files

@@            Coverage Diff             @@
##           v2.7.x    #1068      +/-   ##
==========================================
+ Coverage   81.54%   81.57%   +0.03%     
==========================================
  Files         103      103              
  Lines        5906     5916      +10     
==========================================
+ Hits         4816     4826      +10     
  Misses       1090     1090              

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