[SPARK-58738][SQL] Add parse_command function for SQL statement JSON analysis

[srielau]

What changes were proposed in this pull request?

Add a built-in scalar SQL function parse_command(sqlStmt) that parse-only analyzes a SQL statement string and returns a compact JSON description:

• parse_success and, on failure, a nested STANDARD-format error object (errorClass, messageTemplate, sqlState, messageParameters) so batch evaluation never fails a query on bad SQL
• Statement classification from ISO/IEC 9075-2:2023 Table 39 (statement_identifier, statement_code, statement_type, statement_class); Spark-only statements use product-specific identifiers with negative implementation-defined codes
• Multipart table_references and function_references (identifier part sequences)
• select_list entries with name parts and expression text
• parameter_markers (named and unnamed_count)
• as_subquery for CREATE TABLE ... AS SELECT (still Table 39 CREATE TABLE / code 77)

Why are the changes needed?

Dialect-migration and SQL analysis tooling need an efficient, batchable way to verify that translated SQL parses and to extract statement kind / references without requiring catalog objects to exist.

Does this PR introduce any user-facing change?

Yes. New SQL function:

SELECT parse_command('SELECT a FROM t');
-- {"parse_success":true,"statement_identifier":"SELECT","statement_code":21,...}

SELECT parse_command('SELEC');
-- {"parse_success":false,"error":{"errorClass":"PARSE_SYNTAX_ERROR",...}}

How was this patch tested?

Added ParseCommandResultSuite and ParseCommandSuite (catalyst). Ran:

build/sbt 'catalyst/testOnly org.apache.spark.sql.catalyst.parser.ParseCommandResultSuite org.apache.spark.sql.catalyst.expressions.ParseCommandSuite'

All 13 tests passed.

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