MintFT of x/collection overwrite the minted amount of to account

[zemyblue]

Summary of Bug

Even if we mint a to account with MintFT of x/collection multiple times, only the last minted amount is queried as the final balance. This is because the MintFT of x/collection overwrite a balance of the to account.

finschia-sdk/x/collection/keeper/supply.go

Lines 185 to 195 in 50bd9ed

	func (k Keeper) mintFT(ctx sdk.Context, contractID string, to sdk.AccAddress, classID string, amount sdk.Int) {
	tokenID := collection.NewFTID(classID)
	k.setBalance(ctx, contractID, to, tokenID, amount)
	// update statistics
	supply := k.GetSupply(ctx, contractID, classID)
	k.setSupply(ctx, contractID, classID, supply.Add(amount))
	minted := k.GetMinted(ctx, contractID, classID)
	k.setMinted(ctx, contractID, classID, minted.Add(amount))
	}

Version

v0.47.2
v0.48.0-rc2

Steps to Reproduce

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For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged
• Contributor assigned/self-assigned

[zemyblue]

related in #1106