Add model for `round` build-in function

[jackwener]

Is your feature request related to a problem? Please describe.
#3178 add feature that that specify the floating point accuracy.

We can further improve the feature by adding mode according to the doc of neo4j

Describe the solution you'd like
You can refer to #3178.

What' more, you also refer to the source code of neo4j.

Additional context
None

mentor
@jackwener

If you have any question, you can contact me.

[JayLZhou]

hi i am a newbie for nubula. does this issue still need to be done?

[jackwener]

You can try to test this function in neo4j in its neo4j sandbox.

[harshvardhan-khachane]

Is anybody working on this issue?

[Koukyosyumei]

I am working on this issue!!

[wey-gu]

I am working on this issue!!

Wow 🚀!