Pass optional orgToken configuration variable

[ndowmon]

In Cobalt, API tokens can be valid for multiple organizations. Currently this integration naively assumes that the first organization is the one that users mean to ingest.

https://github.com/JupiterOne/graph-cobalt/blob/master/src/client.ts#L99

  public async getAccount(
    iteratee: ResourceIteratee<CobaltOrg>,
  ): Promise<void> {
    const orgs: CobaltOrg[] = await this.contactAPI(
      'https://api.cobalt.io/orgs',
    );
    await iteratee(orgs[0]);
  }

Instead, when users want to ingest a single organization, they should be able to pass an optional orgToken that they can use to fetch a specific organization.

If the org token is not present, we could either a) ingest just the first organization from https://api.cobalt.io/orgs, or b) ingest all organizations from https://api.cobalt.io/orgs. In the ideal case, each Cobalt organization is associated with a single JupiterOne integration instance.

[nktrk]

Looks good @ndowmon - if the user supplies the Org Token in the UI, that's what should be passed in this header

https://github.com/JupiterOne/graph-cobalt/blob/master/src/client.ts#L80