Prior to this commit, if you had a module structure like
```
| - A.roc
| - Dep
| - B.roc
```
where `B.roc` was defined as
```
interface B exposes [] imports []
```
and `A.roc` was defined as
```
interface A exposes [] imports [Dep.B]
```
The compiler would hang on you. The reason is that even though we expect
`B` to be named `Dep.B` relative to `A`, that would not be enforced.
With this patch, we now enforce such naming schemes - a module must have
the namespaced name it is referenced by. Currently, we determine the
expected namespaced name by looking at how transitive dependencies of the
root module reference the module. In the future, once we have a package
ecosystem and a solid idea of "package roots", we can use the "package
root" to determine how a module should be named.
Closes#4094
This fixed a bug where bindgen was providing cwd() for src_dir,
but actually the src_dir should have been based on the filename.
This prevents that problem from happening in the future!
