Instrument view: bad fontsize when components are small

[jl-wynen]

import scipp as sc
import scippneutron as scn

da = sc.DataArray(
    sc.zeros(sizes={'row': 2}),
    coords={'position': sc.vectors(dims=['row'], values=[[0.0, 0.2, 0.0], [0.0, 0.25, 0.0]], unit='m')})
sample_settings = {
    'center': events.meta['sample_position'],
    'color': '#000000',
    'wireframe': True,
    'size': sc.vector(value=[0.01, 0.01, 0.01], unit=sc.units.m),
    'type': 'box',
}
scn.instrument_view(da, components={'sample': sample_settings})

gives

If it's too difficult to auto-scale the font size, an argument to do it manually would also work.