Uses the fully-qualified module path when getting the module name

[ralexstokes]

The existing implementation would use "local" module name when getting the current module. This caused collisions if there were multiple submodules with the same name. This commit uses the "absolute" module name for a given module so that collisions do not occur.

I ran into this problem as I will put unit tests in a tests module for every module. The implementation of "cargo run tests-in-this-buffer" was using the "local" version so would run all the tests when I just wanted to run a few of the tests (namely those in the current module).

Updating this function to use the fully-qualified name should not break any existing use of this package and provides the functionality I would expect from a function with this name (i.e. run just the tests in this module).