[CALCITE-7774] JDBC adapter generates a GROUP BY with a constant key, which SQL Server rejects - #5257

Jira Link

CALCITE-7774

Changes Proposed

MssqlSqlDialect now returns false from supportsGroupByLiteral(), so SqlImplementor.visitRoot applies AggregateProjectConstantToDummyJoinRule and the constant moves out of the GROUP BY into a dummy join. SQL Server has no form of GROUP BY <constant> it will accept, so there was nothing to fix in the unparsing.

Added MSSQL expectations to testGroupByBooleanLiteral and testGroupByDateLiteral, which already cover Redshift and Informix for the same gate.