Background definition + get_value_for_wavelength causes problems for optical simulations outside of 450 - 1000 nm

[RecurvedBow]

Describe the bug
Commonly, the background of the tissue volume is defined as:
background_dictionary[Tags.MOLECULE_COMPOSITION] = TISSUE_LIBRARY.constant(1e-4, 1e-4, 0.9)

Because this function uses CONSTANT_ABSORBER_ARBITRARY, the background tissue is defined for only the wavelengths 450 nm and 1000 nm. If we run an optical MCX simulation with a wavelength outside of it, it will fail.

Specify a priority (low, medium, high)
medium

To Reproduce
Define any tissue with the background settings and run a optical MCX simulation with a wavelength outside of 450 nor 1000, for example with 400.

Current Behavior
Upon running simulate(pipeline, settings, device), an error is raised:

> volumes = self.create_simulation_volume()
> structure_properties = structure.properties_for_wavelength(wavelength)
> return self.molecule_composition.get_properties_for_wavelength(wavelength)
> (molecule.volume_fraction * molecule.spectrum.get_value_for_wavelength(wavelength))
ValueError: The given wavelength (300) is not within the range of the spectrum (450 - 1000)

Expected behavior
The simulation successfully runs.

Additional context
To fix this, increase this wavelength range or add an min wavelength and max wavelength argument to TISSUE_LIBRARY.constant().

[kdreher]

This is related to #310