fix(core): Convert authentication config source functions to actual functions

[FokkeZB]

IP-127 Zapier Convert: Convert auth config source to functions

Inline functions under auth config objects are not converted to functions by zapier convert, while the test function is:

const testAuth = async (z, bundle) => {
  z.request({
    url: "https://api.wistia.com/v1/account.json",
    method: "GET",
    headers: {
      Authorization: "Bearer {{bundle.authData.access_token}}",
    },
    body: {},
  }).then((response) => response.data);
};

module.exports = {
  type: 'oauth2',
  test: testAuth,
  fields: [],
  oauth2Config: {
    getAccessToken: {
      source:
        "const options = {\n  url: 'https://api.wistia.com/oauth/token',\n  method: 'POST',\n  headers: {\n    'content-type': 'application/x-www-form-urlencoded',\n    accept: 'application/json',\n  },\n  body: {\n    grant_type: 'refresh_token',\n    refresh_token: '{{bundle.authData.refresh_token}}',\n  }\n}\n\nreturn z.request(options)\n  .then((response) => {\n    const results = response.data;\n\n    // You can do any parsing you need for results here before returning them\n\n    return results;\n  });",
    },
  },
};

This PR fixes that my traversing to look for any source: and adds missing test coverage.

[FokkeZB]

@eliangcs this change is likely less controversial and will help with Py2CLI.

[eliangcs]

I tested with a few apps and it works great! I only have a comment on the traverse package version used in package.json. Otherwise, it looks good to me!

[eliangcs]

Thanks! Merging.