repr, expr: roll leap-second timestamps into the next minute

[def-]

chrono represents a parsed :60 second as 59 with nanos >= 1e9, a value
that sorts before the following second while the epoch family (extract
epoch, casts to mz_timestamp, timestamp subtraction, date_bin, precision
rounding) counts it at or past that second. That breaks the monotonicity
contracts persist filter pushdown narrows ranges with: an interior leap
value escapes the endpoint-derived range, so a part holding one could be
wrongly discarded. Roll :60 over at the parse boundary, matching Postgres,
so the leap representation never enters a timestamp. TIME keeps it:
rolling a time over would wrap to 00:00:00 and reverse its ordering, and
the whole-second leap time is provably harmless (fractional leap seconds
are rejected at parse for all types).

add_date_time is the other way a leap representation reached a timestamp.
It passed a leap-second TIME's raw nanos straight through, so DATE + TIME
'23:59:60' still constructed one and disagreed with the equivalent
timestamp literal. It now rolls over the same way.

Both rollovers can overflow chrono's range: TIMESTAMP '262142-12-31
23:59:60' parses, because that is chrono's max date and the leap value
passes the HIGH_DATE check, and adding the rollover second overflows.
Overflow reports out of range in the timestamp, timestamptz, and
DATE + TIME paths instead of panicking.

Closes: PER-63

Builds on top of #38076

[def-]

Superseded by #38109 (same commit, head branch in this repo so it can take part in a GitHub stack). Middle of stack #38111: #38108 → #38109 → #38110.