Is your feature request related to a problem? Please describe.

The minimum and maximum field transforms (which are available in the REST API) have not been implemented in the Firestore Node SDK

Describe the solution you'd like

I imagine the API for this would look very much like FieldValue.increment(...), and would look something like:

// ...
const washingtonRef = db.collection('cities').doc('DC');

// Atomically set the value of population to the minimum of 50 or it's existing value 
const res = await washingtonRef.update({
  population: FieldValue.minimum(50)
});

Describe alternatives you've considered
n/a

Additional context
n/a