Add date_nanos compatibility

[toog]

Hello

Since elastic add date_nanos support, is it possible to add this functionality into date plugin to parse date format like : 2016-06-10T21:42:24.76073899Z with nanosecond precision.

[sliencestorm-wyw]

example
date {
match => ["date", "yyyy/MM/dd HH:mm:ss.SSS.SSS"]
target => "@timestamp"
}
if date value is "20210125 16:00:54.350.008"

but output is "Jan 26, 2021 @ 00:00:54.008" not "350.008"

[TheVastyDeep]

Duplicate of 10822.