Add `nbytes` to repr?

Is your feature request related to a problem?

Would having the nbytes value in the Dataset repr be reasonable?

I frequently find myself logging this separately. For example:

<xarray.Dataset>
Dimensions:  (lat: 25, time: 2920, lon: 53)
Coordinates:
  * lat      (lat) float32 75.0 72.5 70.0 67.5 65.0 ... 25.0 22.5 20.0 17.5 15.0
  * lon      (lon) float32 200.0 202.5 205.0 207.5 ... 322.5 325.0 327.5 330.0
  * time     (time) datetime64[ns] 2013-01-01 ... 2014-12-31T18:00:00
Data variables:
-    air      (time, lat, lon) float32 dask.array<chunksize=(2920, 25, 53), meta=np.ndarray>
+    air      (time, lat, lon) float32 15MB dask.array<chunksize=(2920, 25, 53), meta=np.ndarray> 
Attributes:
    Conventions:  COARDS
    title:        4x daily NMC reanalysis (1948)
    description:  Data is from NMC initialized reanalysis\n(4x/day).  These a...
    platform:     Model
    references:   http://www.esrl.noaa.gov/psd/data/gridded/data.ncep.reanaly...

Describe the solution you'd like

No response

Describe alternatives you've considered

Status quo :)

Additional context

No response

Start at xarray's Dataset repr entry point and inspect how nbytes is currently exposed. Check existing repr-related tests before deciding how the value should appear alongside data variables and dask arrays. Done means Dataset repr includes nbytes with stable formatting and the relevant repr coverage passes.