[Add] Get Accounts and Balances for NeoToken

[cschuchardt88]

Description

--For Offline Usage--
Allows for SDK users to get the accounts of Neo holders with their balances.

Change Log

• Added extension methods GetAccounts and BalanceOf on class NeoToken.

Type of change

• Optimization (the change is only an optimization)
• Style (the change is only a code style for better maintenance or standard purpose)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

• TestGetAccounts
• TestBalanceOf

Test Configuration:

• Unit Tests

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[AnnaShaleva]

LGTM otherwise.

[AnnaShaleva]

It might be useful for external callers to return AccountState instead of just balance. External caller can perform further selection by himself if only balance is needed.

[cschuchardt88]

AccountState only holds balance and AccountState was added for serialization, I believe.

[shargon]

Probably decimals will be soon

[AnnaShaleva]

AccountState only holds balance

I confused AccountState with NeoAccountState. So I mean that for Neo token it might be useful to return NeoAccountState because it contains additional voting information.

Probably decimals will be soon

Hope, it won't happen 🥲