Allow for multiple testnets in dapp data json

[graemeblackwood]

Need to review the structure of the dapp data for dapps that aren't yet on mainnet, and which may be using one of a variety of testnets.

Also need to consider multiple mainnets, e.g. if in future we add Ethereum dapps or other L2s.

[darigovresearch]

Hey @graemeblackwood, thanks for raising this issue! Also think being able to differentiate between testnets and mainnet would be a really helpful feature addition to the current functionality app.

Is this being built in internally at argent or are you accepting pull requests to enable this feature?