[SPARK-39904][SQL][FOLLOW-UP] Rename CSV option prefersDate as preferDate

[gengliangwang]

What changes were proposed in this pull request?

Rename the CSV data source option prefersDate as preferDate.

Why are the changes needed?

All the CSV data source options doesn't have a s on the verb in the naming. For example, inferSchema, ignoreLeadingWhiteSpace and ignoreTrailingWhiteSpace.
The renaming makes the naming consistent.
Also, the title of JIRA https://issues.apache.org/jira/browse/SPARK-39904 uses preferDate as well.

Does this PR introduce any user-facing change?

No, the data source option is not released yet.

How was this patch tested?

Existing UT

[gengliangwang]

cc @sadikovi @HyukjinKwon

[sadikovi]

We discussed before and decided to keep prefersDate similar to a decimal config cc @HyukjinKwon

[gengliangwang]

Hmm, I take a quick check, do you mean the json option prefersDecimal? It is inconsistent with other JSON data source options either https://github.com/apache/spark/blob/master/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/json/JSONOptions.scala#L240 ... Users can make mistakes since they are used to data source options without s on the verb.

Shall we support preferDecimal and prefersDecimal in JSON, and use prefer in the new options of Spark 3.4?

[HyukjinKwon]

im fine w/ that

[sadikovi]

I am curious why did we not do it from the beginning?

[gengliangwang]

I am curious why did we not do it from the beginning?

I didn't join the discussion, but let's make the naming consistent before it is too late. There is only one exception prefersDecimal now.

[gengliangwang]

Thanks, merging to master/3.4