Make facility information for accessible

[nvaytet]

With this, we can now access the properties of the facility pulse (time and wavelength profiles) without creating a source with neutrons (which can be expensive).

import tof
tof.facilities['ess']

FacilityPulse(time=<scipp.DataArray>
Dimensions: Sizes[time:201, ]
Coordinates:
* time                      float64              [s]  (time)  [1.24378e-05, 3.73134e-05, ..., 0.00496269, 0.00498756]
Data:
                            float64  [dimensionless]  (time)  [0.000335837, 0.000711463, ..., 1.1283e-05, 1.05061e-05]

, wavelength=<scipp.DataArray>
Dimensions: Sizes[wavelength:101, ]
Coordinates:
* wavelength                float64             [Å]  (wavelength)  [0.198515, 0.395545, ..., 19.7045, 19.9015]
Data:
                            float64  [dimensionless]  (wavelength)  [0.0247911, 0.0315395, ..., 2.57594e-05, 2.41536e-05]

, frequency=<scipp.Variable> ()    float64             [Hz]  14)

[jl-wynen]

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