fix: YearTransform return years since 1970

[WZhuo]

No description provided.

[WZhuo]

   Types.TimestampType type = Types.TimestampType.withoutZone();
    Literal<Long> ts = Literal.of("2017-12-01T10:12:55.038194").to(type);
    Literal<Long> pts = Literal.of("1970-01-01T00:00:01.000001").to(type);
    Literal<Long> nts = Literal.of("1969-12-31T23:59:59.999999").to(type);

    Transform<Long, Integer> years = Transforms.year();
    assertThat((int) years.bind(type).apply(ts.value()))
        .as("Should produce 2017 - 1970 = 47")
        .isEqualTo(47);
    assertThat((int) years.bind(type).apply(pts.value()))
        .as("Should produce 1970 - 1970 = 0")
        .isZero();
    assertThat((int) years.bind(type).apply(nts.value()))
        .as("Should produce 1969 - 1970 = -1")
        .isEqualTo(-1);

Above is the YearTransform's test case in Java, it should return delta years between the time and 1970.

[zhjwpku]

Good catch, you may also want to change the comments of Transform::Year() and YearTransform.

[wgtmac]

Thanks @WZhuo for fixing this and @zhjwpku for the review!