[FLINK-36865][cdc] Provide UNIX_TIMESTAMP series functions in YAML pipeline

[aiwenmo]

It is reasonable to expect some functions like FROM_UNIXTIME(numeric[, string]), UNIX_TIMESTAMP() and UNIX_TIMESTAMP(string1[, string2]) series functions to help manipulating timestamps without having to write any UDFs.

Function	Janino Code	Description
FROM_UNIXTIME(numeric[, string])	fromUnixtime(NUMERIC[, STRING])	Returns a representation of the numeric argument as a value in string format (default is ‘yyyy-MM-dd HH:mm:ss’). numeric is an internal timestamp value representing seconds since ‘1970-01-01 00:00:00’ UTC, such as produced by the UNIX_TIMESTAMP() function. The return value is expressed in the session time zone (specified in TableConfig). E.g., FROM_UNIXTIME(44) returns ‘1970-01-01 00:00:44’ if in UTC time zone, but returns ‘1970-01-01 09:00:44’ if in ‘Asia/Tokyo’ time zone.
UNIX_TIMESTAMP()	unixTimestamp()	Gets current Unix timestamp in seconds. This function is not deterministic which means the value would be recalculated for each record.
UNIX_TIMESTAMP(string1[, string2])	unixTimestamp(STRING1[, STRING2])	Converts a date time string string1 with format string2 (by default: yyyy-MM-dd HH:mm:ss if not specified) to Unix timestamp (in seconds), using the specified timezone in table config. If a time zone is specified in the date time string and parsed by UTC+X format such as “yyyy-MM-dd HH:mm:ss.SSS X”, this function will use the specified timezone in the date time string instead of the timezone in table config. If the date time string can not be parsed, the default value Long.MIN_VALUE(-9223372036854775808) will be returned.

[aiwenmo]

PTAL @lvyanquan @leonardBang @yuxiqian

[yuxiqian]

Consider adding cases in TransformE2eITCase#testTemporalFunctions

[aiwenmo]

PTAL @yuxiqian

[yuxiqian]

Thanks for @aiwenmo's nice work, UT case seems comprehensive! Just left some trivial comments on typo.

Would @leonardBang like to take a further look?

[leonardBang]

LGTM