Update trace queries to better handle time fields

[aangelisc]

Traces are currently displayed with the wrong timing due to discrepancies between how the trace visualisation handles times and how the Javascript Date type functions (it doesn't correctly handle sub-millisecond precision).

Fixes #888 by converting the time field to nanoseconds and then adjusting it to milliseconds.

[github-actions[bot]]

Use the following command to run this PR with Docker at http://localhost:3000:

  docker run --rm -p 3000:3000 grafana/plugin-builds:012888e6b02e605e9fcd401a9f894d3e5e94d2f4pre

[rudebono]

Thank you ⸜(｡˃ ᵕ ˂ )⸝♡