[SPARK-56659][SQL] Show function resources in DESCRIBE FUNCTION output

[TongWei1105]

What changes were proposed in this pull request?

When a persistent function is created with USING JAR/FILE resources, DESCRIBE FUNCTION does not display those resources in its output.

For example:

CREATE FUNCTION my_udf AS 'com.example.MyUDF' USING JAR 'hdfs:///path/to/my-udf.jar';
DESCRIBE FUNCTION my_udf;

Current output:
Function: spark_catalog.default.my_udf
Class: com.example.MyUDF
Usage: N/A

Expected output:
Function: spark_catalog.default.my_udf
Class: com.example.MyUDF
Usage: N/A
Resource: jar hdfs:///path/to/my-udf.jar

Why are the changes needed?

DescribeFunctionCommand receives ExpressionInfo during analysis, which does not carry FunctionResource metadata. Although the resources are persisted in the metastore via CatalogFunction, they are never retrieved
or displayed by the describe command. This makes it difficult for users to identify which JARs or files a function depends on.

Does this PR introduce any user-facing change?

Yes. DESCRIBE FUNCTION and DESCRIBE FUNCTION EXTENDED now display Resource: rows for persistent functions that were created with USING JAR/FILE/ARCHIVE clauses.

How was this patch tested?

Updated existing tests in SQLQuerySuite to verify that resource information is shown for persistent user-defined functions, covering both DESCRIBE FUNCTION and DESCRIBE FUNCTION EXTENDED.

Was this patch authored or co-authored using generative AI tooling?

Yes, Claude Opus 4.6

[TongWei1105]

cc @wangyum @cloud-fan