Add support for ALL, SOME, ANY in RelToSqlConverter

@Test void testSome() {
  final String sql = "SELECT 1, \"gross_weight\" < SOME(SELECT \"gross_weight\" "
      + "FROM \"foodmart\".\"product\") AS \"t\" "
      + "FROM \"foodmart\".\"product\"";
  final String expected = "";
  sql(sql).ok(expected);
} 

java.lang.AssertionError
    at org.apache.calcite.sql.SqlUtil.unparseBinarySyntax(SqlUtil.java:442)
    at org.apache.calcite.sql.SqlSyntax$4.unparse(SqlSyntax.java:78)
    at org.apache.calcite.sql.SqlOperator.unparse(SqlOperator.java:414)
    at org.apache.calcite.sql.SqlDialect.unparseCall(SqlDialect.java:465)
    at org.apache.calcite.sql.SqlCall.unparse(SqlCall.java:133)
    at org.apache.calcite.sql.SqlAsOperator.unparse(SqlAsOperator.java:81)
    at org.apache.calcite.sql.SqlDialect.unparseCall(SqlDialect.java:465)
    at org.apache.calcite.sql.SqlCall.unparse(SqlCall.java:133)