Refactor `surv_time` to enable cell footnotes #1678

All 775 tests pass, 20 skipped in 1m 19s

      1 files     81 suites 1m 19s ⏱️
  795 tests   775 ✔️   20 💤 0 ❌
1 689 runs 1 050 ✔️ 639 💤 0 ❌

Results for commit 032a0bd.