File and path management

[deltamarnix]

Problem statement

Any component, many blocks, variables, and even parts of variables (e.g. array layers) can be associated with input files (see MF6IO appendix for more details on open/close)

Implementation

Looking into MFFileMgmt. There are only a couple of functions in this class that are supposed to be public.

• copy_files(). Only works when last_loaded_sim_path is not None.
• get_model_path(): Joins sim path with relative model path. If last_loaded_path, it will return those paths.
• get_sim_path(): If last_loaded_path, it will return that path.

The rest of the functions are for internal use only. Most functions are likely to be used in a static manner, but this last loaded path seems to make everything so much more complicated. I am wondering if we could redo the functionality and leave out anything that has to do with last loaded paths. Just give a destination if you want to copy something, for example.

[wpbonelli]

A few related considerations:

• should a simulation have a workspace property or should workspace be a parameter to write_...() methods?
• why have e.g. copy_files() when the user can do that outside of flopy?
• existing workspace approach vs separate input/output directories, cf feature: Separate input and out files in different directories flopy#2462?
• can we disambiguate "binary" vs "external"? These terms seem to have some (maybe a lot of) overlap in flopy3