Add a mapping to tracked locked ZRC20s into Cosmos coins

[lumtis]

Context: #2979 (review)

Add a mapping ZRC20Address -> locked tokens (converted in Cosmos coins) in the store

And add invariant ModuleBalance>LockedTokens

This will be useful for testing when using the simulations testing, doing many operation on the staking we verify there is no unwanted emissions of tokens happening

[kingpinXD]

@lumtis I am not very sure about the invariant mentioned , The ModuleBalance would not be greater that the Locked tokens as we transfer the tokens from the Module to the cosmos address of the user after minting .

[kingpinXD]

Lock ZRC20

• When locking we do the following checks

  • AlreadyLocked : It is the current balance of ZRC20 tokens for the locker account , i.e the bank precompile
  • AmountToDeposit : It is the amount of ZRC20 tokens that the user wants to lock
    We verify that the sum of AlreadyLocked + AmountToDeposit is less than or equal to the total supply of the ZRC20 token.
    Where the total supply is fetched from the the smart contract directly

• An equvalent amount of AmountToDeposit tokens are then locked in the bank precompile account [Transferred from user to bank precompile]

• Once conformed we can Mint the equivalentAmount of cosmos native tokens to the user account

• The total amount minted should always be less than or equal to the amount of ZRC20 tokens locked in the bank precompile account.

Unlock ZRC20

• Check that the caller has enough balance
• Bank Precompile has enough locked ZRC20 to release the tokens
• Send cosmos native tokens from user to fungible module, burn the transferred tokens.
• Send ZRC20 tokens from bank precompile to a user account

Task: Add an invariant to make sure the balance between locked and minted tokens is always maintained
NOTE:

• Burn and Mint automatically adjust supply of cosmos native tokens
• Currently there is only one locker for ZRC20 tokens. The bank precompile .

For all ZRC20 tokens

• Total supply of cosmos native tokens <= Total ZRC20 tokens locked in the bank precompile account

  • Fetch Total supply of cosmos native tokens using bankkeeper.GetSupply(zrc20). Where
    zrc20=ZRC20ToCosmosDenom(zrc20address)
  • Fetch Total ZRC20 tokens locked in the bank precompile account
    lockedAmount, err := k.ZRC20BalanceOf(ctx, zrc20Address, "bankPrecompileAddress")

  Wanted to verify if this is in line with what you were thinking as well ?

[kingpinXD]

• When locking, a mint is always called which would adjust the Supply of cosmos native tokens

• When unlocking a burn is always called which would adjust the Supply of cosmos native tokens

• The check would fail under the conditions

  • We lock tokens and we dont mint
  • We unlock tokens and we dont burn