[appsync-emulator-serverless] Does not respect multiple appsSync API's in config

[barendb]

Back story, we break our yml files into multiple files

ex:

custom: 
  appSync:
    - ${file(src/api/internal-serverless.yml)}

⬆️ that's valid as per serverless-appsync-plugin documentation

However appsync-emulator-serverless assumes that the config will always look like

custom:
  appSync:
    name:  # defaults to api
    ...

Below are the two problem areas
https://github.com/ConduitVC/aws-utils/blob/01f7da7a46c75d3a131d450f0a6d2fbe2c6ade87/packages/appsync-emulator-serverless/server.js#L75

https://github.com/ConduitVC/aws-utils/blob/01f7da7a46c75d3a131d450f0a6d2fbe2c6ade87/packages/appsync-emulator-serverless/schema.js#L395

Happy to create a PR to fix this

[cbaron]

@barendb -- we would love a PR to fix this!

[barendb]

@cbaron #141 here you go ;) It doesn't start multiple API's but it doesn't crash on start-up now