Add TestableERC20Wrapper

[gianfra-t]

Added TestableERC20Wrapper contract in order to replace MockERC20 in tests.

Mint/Burn functions are added that will only be called in tests, and that call corresponding chain extensions for minting/burning specified token.

Refer to Issue #26 from wasm-deploy

[ebma]

Is this ready for review? If so, please add some techies as reviewers.

[gianfra-t]

This is not so much of a very big change but the addition of the ERC20 wrapper with just two methods for testing.

[ebma]

Looks good to me. But the changes to the foucoco-standalone chain-extension that are part of pendulum-chain/wasm-deploy#26 don't exist yet, do they?
Maybe we should first modify that chain-extension before we merge this one, so that we are 100% sure that the required input arguments are what we define here.

[gianfra-t]

Indeed, I have added them to the standalone chain but I couldn't push changes I realize since I don't have access. @ebma if you can could you please give me write access to that repo? I will link those changes here.

[ebma]

Can you try pushing again @gianfra-t? I changed the settings for collaborators.

[gianfra-t]

Thanks! The changes to the chain can be found here.

As part of this changes I have tested and they work as expected.

Perhaps in the future when implementing on foucoco or amplitude, the chain extension definition should be moved to a different file for clarity.

[ebma]

Thanks for linking to the changes on the foucoco-standalone chain, will you create a PR for those as well?

Can confirm that the code of the smart contract looks good now, so it's ready for merge.