feat(spark): add unix date and timestamp functions

[cht42]

Which issue does this PR close?

• Closes [datafusion-spark] add unix_date/micros/millis/seconds functions #19891
• Part of [EPIC] Complete datafusion-spark Spark Compatible Functions #15914

Rationale for this change

Add spark unix date and timestamp functions.

What changes are included in this PR?

New spark functions:

• https://spark.apache.org/docs/latest/api/sql/index.html#unix_date
• https://spark.apache.org/docs/latest/api/sql/index.html#unix_seconds
• https://spark.apache.org/docs/latest/api/sql/index.html#unix_millis
• https://spark.apache.org/docs/latest/api/sql/index.html#unix_micros

Are these changes tested?

yes in slt

Are there any user-facing changes?

yes

[Jefffrey]

We can consider making these (micros, millis, seconds) a unified struct with an inner enum field to differentiate the behaviour, like so:

datafusion/datafusion/spark/src/function/bitwise/bit_shift.rs

Lines 189 to 201 in e5e7636

	#[derive(Debug, Hash, Copy, Clone, Eq, PartialEq)]
	enum BitShiftType {
	Left,
	Right,
	RightUnsigned,
	}
	#[derive(Debug, Hash, Eq, PartialEq)]
	pub struct SparkBitShift {
	signature: Signature,
	name: &'static str,
	bit_shift_type: BitShiftType,
	}

We'd then have different constructors:

datafusion/datafusion/spark/src/function/bitwise/bit_shift.rs

Lines 253 to 263 in e5e7636

	pub fn left() -> Self {
	Self::new("shiftleft", BitShiftType::Left)
	}
	pub fn right() -> Self {
	Self::new("shiftright", BitShiftType::Right)
	}
	pub fn right_unsigned() -> Self {
	Self::new("shiftrightunsigned", BitShiftType::RightUnsigned)
	}

Which can be used like so:

datafusion/datafusion/spark/src/function/bitwise/mod.rs

Lines 27 to 41 in e5e7636

	make_udf_function!(
	bit_shift::SparkBitShift,
	shiftleft,
	bit_shift::SparkBitShift::left
	);
	make_udf_function!(
	bit_shift::SparkBitShift,
	shiftright,
	bit_shift::SparkBitShift::right
	);
	make_udf_function!(
	bit_shift::SparkBitShift,
	shiftrightunsigned,
	bit_shift::SparkBitShift::right_unsigned
	);

[cht42]

sounds good, updated