Standardize options handling across providers (pointer to struct vs. pointer)

[arnab-chaudhuri-c2fo]

Right now withOptions under file system takes an empty interface{} that can handle a pointer or a struct.

There is no code in place to set the options from a pointer to options passed to an interface.

Also, it seems Azure has a pointer to an Azure option item vs. using the standard interface from vfs. We should look at pros and cons here and standardize.

These should be addressed in refactor work.