Support `float` arguments to `to_timestamp` function

[alamb]

Is your feature request related to a problem or challenge?

In #7844 we are (about to) change to_timestamp to be aligned with postgres by taking seconds instead of milliseconds.

To fully align with postgres, we should also add support double (Float64) arguments as well

The postgres documentation for to_timestamp is here

Describe the solution you'd like

I would like the to_timestamp function to also support Float64 point arguments:

For example, (not the 1.1 at the end of the timestamp)

willy=# select to_timestamp(1.1);
       to_timestamp       
--------------------------
 1970-01-01 08:00:01.1+08

Describe alternatives you've considered

No response

Additional context

Note the string / two argument version of to_timestamp is covered by #5398

[spaydar]

I'll work on this

[alamb]

Thanks @spaydar -- note that we haven't merged #7844 yet, so you probably would need to start from that branch if you want to work on this prior to when @comphead merges

[edmondop]

Is this still up for grab?

[spaydar]

I'm still working on this; it's been a bit more involved than I expected. Is this blocking other issues?

[comphead]

No blocking issues as of now, rather this is one of the missing pieces for timestamp.
But I would not hurry with that, its tightly connected with some issues from #7958 (comment)