* loadtime: add block time to the data point (#9484)

This pull request adds the block time as the unix time since the epoch to the `report` tool's csv output.

```csv
...
a7a8b903-1136-4da1-97aa-d25da7b4094f,1614226790,1663707084905417366,4,200,1024
a7a8b903-1136-4da1-97aa-d25da7b4094f,1614196724,1663707084905417366,4,200,1024
a7a8b903-1136-4da1-97aa-d25da7b4094f,1613097336,1663707084905417366,4,200,1024
a7a8b903-1136-4da1-97aa-d25da7b4094f,1609365168,1663707084905417366,4,200,1024
a7a8b903-1136-4da1-97aa-d25da7b4094f,1617199169,1663707084905417366,4,200,1024
a7a8b903-1136-4da1-97aa-d25da7b4094f,1615197134,1663707084905417366,4,200,1024
a7a8b903-1136-4da1-97aa-d25da7b4094f,1610399447,1663707084905417366,4,200,1024
...
```

#### PR checklist

- [ ] Tests written/updated, or no tests needed
- [ ] `CHANGELOG_PENDING.md` updated, or no changelog entry needed
- [ ] Updated relevant documentation (`docs/`) and code comments, or no
      documentation updates needed

(cherry picked from commit 5fe1a72416722f8045b863fa0c7c045de583b6a1)

* lint fix

Co-authored-by: William Banfield <4561443+williambanfield@users.noreply.github.com>
Co-authored-by: William Banfield <wbanfield@gmail.com>