Setting both width and grid of a flame should raise an exception

[speth]

Problem description

In Python, specifying both a width and a grid to any type of flame object results in the grid getting replaced with the default grid of the given width. Instead, this overdefinition of the grid should raise an exception.

Steps to reproduce

>>> f = ct.CounterflowDiffusionFlame(gas, width=0.1, grid=np.linspace(0, 0.2, 20))
>>> print(f.grid)
array([0.  , 0.02, 0.04, 0.06, 0.08, 0.1 ])

System information

• Cantera version: 3.1.0a2 / main branch at d37a76bf6

Additional context

Originally reported on Users' Group: https://groups.google.com/g/cantera-users/c/GBJtoDBvulY