isthmus: SubstraitToSql with Calcite's built-in dialects renders interval and LTZ casts their engines reject #1350

SubstraitToSql renders interval and TIMESTAMP WITH LOCAL TIME ZONE casts with Calcite's built-in PostgresqlSqlDialect and SparkSqlDialect in a form the target engine rejects. SubstraitSqlDialect overrides getCastSpec for intervals since #1346, but the Calcite dialects still use their default cast spec.

Measured on main at bc050d3, with CREATE TABLE t (ts9 TIMESTAMP(9), ltz3 TIMESTAMP(3) WITH LOCAL TIME ZONE, ltz6 TIMESTAMP(6) WITH LOCAL TIME ZONE, i INT):

SELECT ts9 + i * INTERVAL '1' DAY FROM t
  Substrait:  ... CAST(I * INTERVAL '1 00:00:00' DAY TO SECOND(6) AS INTERVAL DAY TO SECOND(9)) ...
  PostgreSQL: ... CAST("I" * INTERVAL '1 00:00:00' DAY TO SECOND(6) AS INTERVAL_DAY_SECOND(10, 9)) ...
  Spark:      ... CAST(`I` * INTERVAL '1 00:00:00' DAY TO SECOND(6) AS INTERVAL_DAY_SECOND(10, 9)) ...

SELECT CAST(ltz6 AS TIMESTAMP(3) WITH LOCAL TIME ZONE) FROM t
  PostgreSQL: SELECT CAST("LTZ6" AS TIMESTAMP(3) WITH LOCAL TIME ZONE) FROM "T"
  Spark:      SELECT CAST(`LTZ6` AS TIMESTAMP(3) WITH LOCAL TIME ZONE) FROM `T`

PostgreSQL 14 rejects the first with type "interval_day_second" does not exist and the second with syntax error at or near "WITH"; INTERVAL DAY TO SECOND(6) and TIMESTAMP(3) WITH TIME ZONE run. The Spark output was not run against Spark.

The LTZ form is reachable from any explicit cast. #1346 makes both more common for datetime arithmetic, since a mixed-precision ts ± interval now widens the narrower operand with a cast (ltz3 + INTERVAL '5' DAY renders CAST(LTZ3 AS TIMESTAMP(6) WITH LOCAL TIME ZONE) in every dialect).

The Calcite dialects are not isthmus's to override, so this likely belongs with the dialect-boundary rendering in #1013.