Add optional, per-query parameters for providing a traceparent and tags

[trevor-fauna]

Notes

FE-2382

Adds new, optional headers to driver, traceparent and tags, for providing a unique identifier per-query identifier, as well as KV-pair tags, to each submitted query. README was updated as well:

---

traceparent

A W3C-compliant identifier for enabling distributed tracing across different
vendors. If not provided, one is automatically generated server-side and attached to the query. See
Trace Context spec for more details.

var data = client.query(q.Paginate(q.Collections()), {
  traceparent: "00-c91308c112be8448dd34dc6191567fa0-b7ad6b7169203331-01",
})

tags

Allows for associating user-provided tags with a query.

var data = client.query(q.Paginate(q.Collections()), {
  tags: { key1: "value1", key2: "value2" },
})

---

How to test

Test cases were added to assert the new fields. They can be executed via yarn test.

[mwilde345]

return Object.entries(tags).map(e => e.join('=')).join()

maybe we want to validate the key:value pairs

silently throw out bad ones

let invalidTag = (value => [undefined, "", null].includes(value))
return Object.entries(tags)
  .filter(e => !e.some(invalidTag))
  .map(e => e.join('=')).join() 

Exception

let invalidTag = (value => [undefined, "", null].includes(value))
return Object.entries(tags)
  .map(e => {
    if (e.some(invalidTag)){
      throw new Error(`Invalid tag: ${e}`)
    }
    return e.join('=')
  }).join() 

[faunaee]

Missing ',' from the final join. Seems like it should be:

return Object.entries(tags).map(e => e.join('=')).join(',')

[mwilde345]

comma is the default, but yes better to be verbose

[trevor-fauna]

return Object.entries(tags).map(e => e.join('=')).join(',')

Much cleaner, thanks.

maybe we want to validate the key:value pairs
silently throw out bad ones

Exception is preferred to silently discarding. The only reason we silently discard invalid traceparents is because the W3C spec defines it that way, but in general, we should try to consider customer requests immutable. That said, let me sync with product on a reasonable length of tags and update that in a separate PR.

[cleve-fauna]

trim the keys and values?

reject empty/blank keys?

example code to help clarify:

 > x = {'': 'dog'}
{ '': 'dog' }
 > ' cat '.trim()
'cat'

[trevor-fauna]

Yeah, gonna add validation in a follow-up (including max key/value length, etc.).