Path/Module resolve callback

[santiberna]

While working with wrenbind17, I have found the library quite lacking in handling wren imports for files. The original wren library includes a module resolution callback so that things like relative imports and path aliasing problems can be handled correctly. Wrenbind17 does not expose this feature of wren to the user and using the vector of import paths is quite limited.

This pull request fixes that by adding a pathResolveFn to the vm class with an appropriate setter, quite like the printFn and loadModuleFn. This also changes the signature of LoadModuleFn, since it no longer requires the vector of import paths as inputs (since it only needs the resolved output of pathResolveFn).

The default implementation for the path resolution function simply contains the resolution part of the old LoadModuleFn that checks for a valid path based on the import paths. This maintains the behaviour of the library and should not break users that don't want to use this feature.

If I missed anything or you have any tweaks I should consider, please let me know 👍

[matusnovak]

This is pretty good! Looks good to me. Thanks! Merging.