`r1_to_project_class` fails on some of the RasCAL-1 demo projects

r1_to_project_class cannot successfully convert the 8 contrast monolayer example from RasCAL-1 or the motofit benchmark example, both of which produce the error:

>>> r1_to_project_class('Monolayer_8_contrasts.mat')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/rec93639/Code/python-RAT/RATapi/utils/convert.py", line 208, in r1_to_project_class
    [
  File "/home/rec93639/Code/python-RAT/RATapi/utils/convert.py", line 211, in <listcomp>
    thickness=params[thickness - 1].name,
TypeError: unsupported operand type(s) for -: 'str' and 'int'

nor the double bilayer volume model (although this one may be an issue with the actual MAT judging by the error message:

>>> r1_to_project_class('double_bilayer_volume_model.mat')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/rec93639/Code/python-RAT/RATapi/utils/convert.py", line 116, in r1_to_project_class
    back_params = read_param("back_param_names", "backs_constr", "backs", "backgrounds_fityesno")
  File "/home/rec93639/Code/python-RAT/RATapi/utils/convert.py", line 83, in read_param
    [
  File "/home/rec93639/Code/python-RAT/RATapi/utils/convert.py", line 84, in <listcomp>
    Parameter(
  File "/home/rec93639/Code/python-RAT/.venv/lib/python3.10/site-packages/pydantic/main.py", line 176, in __init__
    self.__pydantic_validator__.validate_python(data, self_instance=self)
pydantic_core._pydantic_core.ValidationError: 1 validation error for Parameter
  Value error, value 3.0506581195417703e-12 is not within the defined range: 5e-08 <= value <= 7e-06 [type=value_error, input_value={'name': 'Background para...loat64(7e-06), 'fit': 0}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.7/v/value_error

nor the spline test:

>>> r1_to_project_class('splineTest.mat')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/rec93639/Code/python-RAT/RATapi/utils/convert.py", line 42, in r1_to_project_class
    layer_model = LayerModels(layer_model)
  File "/usr/lib/python3.10/enum.py", line 385, in __call__
    return cls.__new__(cls, value)
  File "/usr/lib/python3.10/enum.py", line 710, in __new__
    raise ve_exc
ValueError: 'Custom XY Profile' is not a valid LayerModels

The remaining examples run successfully. Improve the robustness of the converter and maybe add the remaining RasCAL-1 demo projects as test cases.

RascalSoftware / python-RAT

`r1_to_project_class` fails on some of the RasCAL-1 demo projects #93