Timestamp normalization

[cwfitzgerald]

Connections

Closes #6719.

Should land after #7140.

Description

Automatically normalizes all timestamps to be in units of nanoseconds instead of the arbitrary unit gpus use.

Testing
Manually so far.

Squash or Rebase?

Squash

Checklist

• Run cargo fmt.
• Run taplo format.
• Run cargo clippy. If applicable, add:
  • --target wasm32-unknown-unknown
• Run cargo xtask test to run tests.
• If this contains user-facing changes, add a CHANGELOG.md entry.