Fix issue tx verification

[roman-khimov]

Problem

Missing some checks for Issue transactions.

Solution

Add them.

[codecov]

Codecov Report

Merging #765 into master will increase coverage by 0.37%.
The diff coverage is 60%.

@@            Coverage Diff             @@
##           master     #765      +/-   ##
==========================================
+ Coverage   64.45%   64.82%   +0.37%     
==========================================
  Files         141      139       -2     
  Lines       12881    12664     -217     
==========================================
- Hits         8302     8209      -93     
+ Misses       4177     4056     -121     
+ Partials      402      399       -3

Impacted Files	Coverage Δ
pkg/core/blockchain.go	44.44% <0%> (+2.43%)	⬆️
pkg/core/mempool/mem_pool.go	97.2% <100%> (+0.11%)	⬆️
pkg/core/state/account.go	58.75% <0%> (-25.54%)	⬇️
pkg/wallet/wallet.go	76.11% <0%> (-6.6%)	⬇️
pkg/rpc/request/txBuilder.go	50.67% <0%> (-1.41%)	⬇️
pkg/core/dao.go	68.68% <0%> (-1.15%)	⬇️
pkg/rpc/server/server.go	84.71% <0%> (-0.12%)	⬇️
pkg/rpc/client/nep5.go	0% <0%> (ø)	⬆️
pkg/rpc/response/result/unclaimed.go	0% <0%> (ø)	⬆️
pkg/core/storage/store.go	37.5% <0%> (ø)	⬆️
... and 10 more

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