Parse datetimes using Google's format

[dmosorast]

Description of change

Correct the datetime parsing behavior for fields in the Time group. These come back using non-ISO types, so they were being rejected by the Transformer.

This adds a step before writing the records that will parse them as datetimes and convert them to ISO-8601 format (at UTC timezone).

QA steps

• automated tests passing
• manual qa steps passing (list below)
  • Ran through a manual sync and inspected the values at each conversion step.

Risks

• Medium, I'm adding a new field to the datetime types mapping, which could result in mixed datatypes for some users.

Rollback steps

• revert this branch, bump patch version and re-release

[luandy64]

This would've looked nicer with a clojure thread-first, but 👍