Address contents tsconfig.json in AssemblyScript

There are multiple `tsconfig.json` files whose contents were generated with relative paths on a dev machine. Example:

https://github.com/casper-network/casper-node/blob/2115b58c96773d6c4b53611d8ea771f83ca21a1b/smart_contracts/contracts_as/test/groups/assembly/tsconfig.json#L1-L6

We should address this and decide whether we can make use of files, or is it safe to completely remove those.