[SPARK-43485][SQL] Fix the error message for the unit argument of the datetime add/diff functions

[MaxGekk]

What changes were proposed in this pull request?

In the PR, I propose to extend the grammar rule of the DATEADD/TIMESTAMPADD and DATEDIFF/TIMESTAMPDIFF, and catch wrong type of the first argument unit when an user pass a string instead of an identifier like YEAR, ..., MICROSECOND. In that case, Spark raised an error of new error class INVALID_PARAMETER_VALUE.DATETIME_UNIT.

Why are the changes needed?

To make the error message clear for the case when a literal string instead of an identifier is passed to the datetime ADD/DIFF functions:

spark-sql (default)> select dateadd('MONTH', 1, date'2023-05-11');
[WRONG_NUM_ARGS.WITHOUT_SUGGESTION] The `dateadd` requires 2 parameters but the actual number is 3. Please, refer to 'https://spark.apache.org/docs/latest/sql-ref-functions.html' for a fix.; line 1 pos 7

Does this PR introduce any user-facing change?

Yes, it changes the error class.

After the changes:

spark-sql (default)> select dateadd('MONTH', 1, date'2023-05-11');

[INVALID_PARAMETER_VALUE.DATETIME_UNIT] The value of parameter(s) `unit` in `dateadd` is invalid: expects one of the units without quotes YEAR, QUARTER, MONTH, WEEK, DAY, DAYOFYEAR, HOUR, MINUTE, SECOND, MILLISECOND, MICROSECOND, but got the string literal 'MONTH'.(line 1, pos 7)

== SQL ==
select dateadd('MONTH', 1, date'2023-05-11')
-------^^^

How was this patch tested?

By running the existing test suites:

$ PYSPARK_PYTHON=python3 build/sbt "sql/testOnly org.apache.spark.sql.SQLQueryTestSuite"

[MaxGekk]

I do believe the failed test suite HealthTrackerIntegrationSuite is not related to my changes. Though, I have checked it locally.

Merging to master. Thank you, @HyukjinKwon and @cloud-fan for review.