[Feature Request] Add stateless function now() to get the current local time

[mbresson]

Hi,
it would be nice to have a function now() returning the current local time, as it could be used in conjunction with unixNano() to create alert conditions by comparing a timestamp stored in any field with the current time (as discussed in this discussion thread).

For instance, it could be used like so:

batch
  |query('''SELECT * FROM "mydb"."autogen"."subscription"''')
    .period(10h)
    .every(10s)
  |alert()
    .crit(lambda: "expiration" < unixNano(now()))
    .log('/tmp/dates-alerts.log')