[Bugfix] protos with the same package name prefix fail to compile

[houqp]

When proto files sharing the same package name prefixes reference types from each other, protoc_wrapper will generate code with incorrect module scope resulting in the following compilation error:

error[E0412]: cannot find type `CMessage` in module `super`
  --> bazel-out/darwin_arm64-fastbuild/bin/proto/prost/private/tests/shared_package_prefix/shared_pkg_prefix_proto.lib.rs:21:46
   |
21 |         pub c: ::core::option::Option<super::CMessage>,
   |                                              ^^^^^^^^ not found in `super`
   |
help: consider importing this struct
   |
15 +     use crate::pkg::CMessage;
   |
help: if you import `CMessage`, refer to it directly
   |
21 -         pub c: ::core::option::Option<super::CMessage>,
21 +         pub c: ::core::option::Option<CMessage>,

This Patch refactors the module tree walk implementation to ensure generated rust code are wrapped with the correct rust module hierarchy.

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[houqp]

@UebelAndre the CI error looks like infra related and not caused by my change?

[stevebarrau]

/cc @freeformstu