Deprecate old ways of creating ParameterValues

[valentinsulzer]

I think the transition to using python files or json file (BPX) for parameter values has gone fairly well so we can start to deprecate some of the old methods for importing values from csv files. These are no longer recommended but still possible from the codebase. We should also update the training videos on this very soon.

• remove functionality to update from chemistry (old approach with separate files for anode/cathode/electrolyte etc)
• remove functionality to load from csv
• remove functionality to load a function from a string "[function]function_name"
• remove functionality to load data from a string "[data]data_name"

Basically, users will be responsible for passing in a python dictionary where functions are python functions. Interpolants can be created as functions like this

This is a breaking change so let's discuss before committing

[brosaplanella]

Shall we keep these options with a warning for a few releases and then remove?

[valentinsulzer]

We've had this warning up for ~6 releases

PyBaMM/pybamm/parameters/parameter_values.py

Line 65 in 18d4e84

warnings.warn(

[brosaplanella]

Then happy to deprecate it :)