The unqualified-call scope added for #4001 collected every `import` and
`use` in a file into one list, so an import in one module leaked into a
sibling module defined in the same file: `MyApp.Sibling.go/1` calling
`fmt(x)` still bound to `MyApp.Helpers.fmt/1` because `MyApp.Importer`
imported it. Elixir scopes `import`/`use` to the module body it appears
in and to the modules nested in it.
Record targets per enclosing module, with the file's top level as its
own scope, and build each call's scope from its own module, the modules
enclosing it, and the top level. Each raw call now gets its own list
rather than sharing one mutable list with every other call in the file.
A module nested in a same-named module shares its node id, so the walk
up the enclosing chain stops at a module it has already visited.
Follow-up to #4015. Refs #4001
Ayushraj06-bit
e508142dac