fix create wallet, calling getpasswordhash less times

[melanke]

No description provided.

[codecov]

Codecov Report

Merging #200 into development will increase coverage by 0.02%.
The diff coverage is 75%.

@@               Coverage Diff               @@
##           development     #200      +/-   ##
===============================================
+ Coverage        40.89%   40.91%   +0.02%     
===============================================
  Files              223      223              
  Lines             8337     8340       +3     
===============================================
+ Hits              3409     3412       +3     
  Misses            4928     4928

Impacted Files	Coverage Δ
src/NeoSharp.Application/Client/Prompt[Wallet].cs	0% <0%> (ø)	⬆️
src/NeoSharp.Core/Wallet/NEP6/NEP6WalletManager.cs	77.34% <85.71%> (+0.22%)	⬆️

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