Nanosecond support in Logs UI

I found the same issue while indexing on nanoseconds.

My work around to keep Logs UI working is to include two timestamps in the events: The standard @timestamp in milliseconds and a second one @timestamp_nanoseconds.

I made @timestamp_nanoseconds the Time Field in the Index Pattern and this allows Discovery to use nanoseconds. While at the same time Logs UI is happy when it finds @timestamp.

Some details over here.

I hope it helps.