Extend ILP to allow to set non-designated timestamp column to current server timestamp

Is your feature request related to a problem?

Sometime it's useful to see the difference between the event timestamp and the timestamp it is got written in QuestDB. To do that a column with server timestamp auto generated by QuestDB is needed.

Describe the solution you'd like.

Add feature to ILP parser to write server timestamp to a column

table,ticker=BTC price=123.42,server_timestamp=now() 1652971930000000000

I suggest using syntax now() because it's relatively short and descriptive

This should create table

column	type	value
ticker	Symbol	BTC
price	Double	123.42
server_timestamp	Timestamp	2022-05-19T14:52:12
timestamp	Timestamp	2022-05-19T14:52:10

Describe alternatives you've considered.

Alternative would be to add default value in table create statement. Defaults are useful on their own and deserve their own issue.

Adding syntax to ILP will still be useful since many users do not pre-create tables before sending ILP data

Additional context.

No response