Validate config

Need add validation for:

* require options from config
* available formats
* available transforms
* available actions
* available platforms

If validation failure return promise reject from build:

```js
export function build(config) {
const [isValid, errors] = validate(config)
if (!isValud) {
return Promise.reject(errors)
}
}
```

Start at the build(config) entry point and trace how configuration is currently consumed, then locate or establish the validate(config) flow. Confirm how required options and supported formats, transforms, actions, and platforms are represented. Done means invalid configuration causes build to return a rejected promise with the validation errors; no file or test is named in the issue.

Written by the indexing model from the issue text.