core, services: fix Designation-dependant service initialisation

[AnnaShaleva]

1. Initialise services dependant on roles designation based on N+1 block so that Genesis roles extension work properly. There's not much sence to fetch node roles information for the latest persisted block because Designation contract itself makes designated nodes responsible since the next subsequent block.
2. Perform initialisation of StateRoot service with designated StateValidator's node list in the service constructor. There's no need to wait until the next role update event, and it may lead to inaccuraces in service work on SIGHUP/server restart.

Close #3228.

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (4216efb) 85.38% compared to head (15b4e0a) 85.30%.

Files	Patch %	Lines
pkg/services/stateroot/service.go	66.66%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3229      +/-   ##
==========================================
- Coverage   85.38%   85.30%   -0.08%     
==========================================
  Files         326      326              
  Lines       43988    44007      +19     
==========================================
- Hits        37557    37540      -17     
- Misses       4951     4987      +36     
  Partials     1480     1480              

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