Add FirstTriggerLogEntry and CommonLogEntryField fields and json tags

[afarbos]

first_trigger_log_entry contain way more than just an APIObject.
This PR intend to add all fields that are (un)marshall from the first_trigger_log_entry

[afarbos]

@stmcallister if you have a chance to look at this PR.
Thanks,

[stmcallister]

@afarbos Thanks for making this contribution! However, I'm not able to get additional fields to come back on the first_trigger_log_entry object on the incidents endpoint. Using POSTMAN I only see id, type, summary, self and html_url (essentially, just the APIObject fields. Can you share how you're getting the additional fields?

[afarbos]

Did you include first_trigger_log_entries? see the original request:

{
  "method": "get",
  "url": "https://api.pagerduty.com/incidents",
  "query": {
    "include[]": "first_trigger_log_entries"
  },
  "headers": {
    "Accept": "application/vnd.pagerduty+json;version=2",
    "Authorization": "Token token=*********************"
  }
}

You could also use pd from this repo like this:

make build && ./pd incident list --include first_trigger_log_entries

[stmcallister]

thank you for this!