Smart contract all source code endpoint

[lukeromanowicz]

Implement GET /contracts/:id/source endpoint that returns all of the Smart Contract files as an array.

❌ If the contract with the id provided in the PATH doesn’t exist or has not been verified, the response will be an error HTTP 404

✅ If the contract has been verified the response will be HTTP 200 with an array of the following records representing each of the source code files:

{
  source: [{
    filePath: string
    isEntryFile: boolean
    content: string
  }]
}