Update genesis generation script

[mattdean-digicatapult]

Pull Request

Checklist

• Have you read Digital Catapult's Code of Conduct?
• I have performed a self-review of my own 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.

PR Type

Please delete options that are irrelevant.

• Bug Fix
• Chore
• Feature
• Documentation Update
• Code style update (formatting, local variables)
• Breaking Change (fix or feature that would cause existing functionality to change)

Linked tickets

https://digicatapult.atlassian.net/browse/SQNC-95

High level description

Updates the genesis script following the introduction of the the session and validatorSet pallets

Detailed description

Following digicatapult/sqnc-node#233 new chains should use an updated genesis format whereby validators are set in the session and validatorSet pallets. Note a few other changes here:

• updated logic so a new account is created as owner of each node. This is required by the session pallet
• updated documentation to actually match the script
• removed balance as an input as transactions aren't charged for. A nominal balance is still added to ensure account existance
• removed unused functions assert_balance and create_node_identity
• merged functions assert_node_valid and assert_account_valid as we need to make sure names don't overlap between the two and the functionality became equivalent

Describe alternatives you've considered

None

Operational impact

None

Additional context

None

[mattdean-digicatapult]

This is draft as we want to generate an old style genesis for staging to test the upgrade