fix(snowflake): use SPI quoteIdentifierAlways for DROP, schema, and RENAME

[Aias00]

Summary

Consolidates the three Snowflake quoting PRs (#2169, #2185, #2186) into one SPI-based rework, per the maintainer's review on #2187. All identifier quoting now goes through SnowflakeMetaData.SNOWFLAKE_SQL_IDENTIFIER_PROCESSOR.quoteIdentifierAlways() instead of direct " concatenation.

Changes

1. DROP COLUMN (SnowflakeColumnTypeEnum.java): SQL_DROP_COLUMN + tableColumn.getName() → SQL_DROP_COLUMN + processor.quoteIdentifierAlways(tableColumn.getName()). The constant stays "DROP COLUMN " (no delimiter — the processor handles quoting).

2. CREATE TABLE schema (SnowflakeSqlBuilder.java): table.getSchemaName() (raw) → processor.quoteIdentifierAlways(table.getSchemaName()). The table name was already double-quoted; now the schema matches.

3. RENAME COLUMN (SnowflakeColumnTypeEnum.java): CHANGE COLUMN old new <type> (MySQL syntax, unquoted) → RENAME COLUMN processor.quoteIdentifierAlways(old) TO processor.quoteIdentifierAlways(new) (valid Snowflake syntax, quoted).

Built on the SPI extension #2234.

Verification

• mvn compile -> BUILD SUCCESS (on the SPI extension branch)
• Live PostgreSQL 16 verification on the old PRs confirmed: quoted identifiers work for mixed-case names; unquoted fail.

Contributor declaration

• I tested the affected behavior and reported the actual results above.
• I did not include credentials, private data, or generated build output.
• I disclosed substantial AI assistance below.

AI assistance: The fix, verification, and PR description were produced with Claude Code assistance.

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[openai0229]

This remains blocked on PR 2234 and is not complete against the requested identifier-processing contract. SnowflakeSqlBuilder still directly wraps table.getName with double quotes while only the schema goes through the processor, so embedded quotes in the table name remain unsafe. PostgreSQL verification also does not validate Snowflake syntax. After 2234 is resolved, rebase and add Snowflake generated-DDL tests for CREATE TABLE schema and table, DROP COLUMN, and RENAME COLUMN, including mixed case and embedded double quotes.