[roll] Roll fuchsia [zircon][time] Ensure that the TimeValues structure is always completely initialized.

Make certain that the TimeValues structure shared with user-mode via
read-only VMO has always been completely initialized at construction
time.  Specifically:

+ Replace uses of `bool` with `uint8_t` so that we don't need to pull
  fancy tricks to get the padding amount correct.  `bool` does not
  have a defined size in the standard, but uint8_t does.
+ Make sure that the structure is explicitly padded out to an 8 byte
  boundary, and that those padding bytes are always initialized.

Original-Original-Fixed: 515184484
Original-Original-Bug: 515456595
Original-Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1622379
Original-Original-Revision: 30bb700cfd53134c7e0d11604c44ce959fc8241e
GitOrigin-RevId: 573a7e986fe69f67d76d79f45ecfff0998544c08
Change-Id: I4b6555556a4ede23cf78e88768c367d956086d07
Reviewed-on: https://fuchsia-review.googlesource.com/c/integration/+/1628754
Cr-Commit-Position: refs/heads/main@{#193527}