fix: parse INTERVAL column type with time-unit qualifier

[fudianchn]

What

Consume the optional time-unit qualifier (<unit> [TO <unit>]) after an INTERVAL column data type, so PostgreSQL/Oracle CREATE TABLE statements such as len interval hour to minute parse and round-trip correctly.

Why

Per the PostgreSQL docs (sql-createtable), interval hour to minute is a valid column type. JSQLParser currently rejects it:

net.sf.jsqlparser.JSQLParserException: Encountered unexpected token: "hour" <K_DATE_LITERAL>

Root cause

In ColDataType, INTERVAL is matched as the type name via the reserved-keyword-as-identifier fallback, but the following time-unit qualifier — tokenized as K_DATE_LITERAL (YEAR|MONTH|DAY|HOUR|MINUTE|SECOND), optionally followed by K_TO <K_DATE_LITERAL> — was not consumed, so the next token (hour) triggered a parse error.

How

After the type token is matched in ColDataType, optionally consume [<K_DATE_LITERAL> [<K_TO> <K_DATE_LITERAL>]] and append it to the data type string. The consumption is gated by a semantic-predicate LOOKAHEAD({ tk.kind == K_INTERVAL && getToken(1).kind == K_DATE_LITERAL }), so it only applies to an INTERVAL type immediately followed by a time unit — other types are unaffected, and the existing interval(...) precision form (parenthesised-arguments branch) keeps working. The qualifier text is read from the matched tokens' images, so deparse preserves the original casing and round-trips.

Limitation

The leading/fractional precision form interval day(2) to second(6) is not covered — only the bare <unit> [TO <unit>] form reported in the issue. This keeps the change surgical; precision-with-qualifier can be addressed in a follow-up.

Testing

• New ColDataTypeTest#testIntervalQualifierIssue1728 (round-trip + AST assertion that the qualifier is attached to the column's data type) and #testIntervalQualifierYearToMonthIssue1728 — both fail before the grammar change (parse error) and pass after.
• ./gradlew test --tests net.sf.jsqlparser.statement.create.table.ColDataTypeTest — green.
• Full ./gradlew test — no regressions introduced by this change. The 33 unrelated failures observed locally are pre-existing environmental issues (Mockito inline MockMaker does not initialise under the local JDK 17 / Windows toolchain, and ParserKeywordsUtilsTest resolves its temp file to C:\WINDOWS); both reproduce on unmodified master.

Fixes #1728