Adjust contract config structure to specify source files for aliases

[psiemens]

Issue To Be Solved

The current alias structure works for resolving contract aliases during deployment, but it does not provide a way for code editors (e.g. VS Code) to resolve imports locally and perform semantic checking without reading from the chain.

Suggest A Solution

We can update the flow.json config structure to specify a source file for all contracts. This source file is resolved when developing locally, but is then replaced with the appropriate alias during deployment.

  "contracts": {
    "NonFungibleToken": {
      "source": "./cadence/kittyItems/contracts/NonFungibleToken.cdc",
      "aliases": {
        "testnet": "0xABC"
      }
    },
    "FungibleToken": {
      "source": "./cadence/kittyItems/contracts/FungibleToken.cdc",
      "aliases": {
        "emulator": "0xABC",
        "testnet": "0xABC"
      }
    }
  }