fix: Correct module naming and registration

[MarquessV]

Closes #21

As a workaround to pyo3#759, create_init_submodule! updates sys.modules to register a module. sys.modules is a mapping of the fully qualified path to a module, to the module object itself. create_init_submodule! was using the fully qualified path as both the key and the name of the module. This made submodule import paths awkward to work with, especially with tooling, and in some cases it even breaks imports.

For example, quil-py defines a module quil, with submodules expression, instructions, program, and validation.

Using the current release of rigetti-pyo3, notice the repetition of quil.expression when inspecting the quil module. This repetition also breaks the import quil.expression syntax, because the real path is quil.quil.expression but that module is impossible to access with the usual import syntax, since quil.quil.expression is recognized as three modules delimited by a . by Python, but really it's just two modules, "quil" and "quil.expression".

After this fix, the quil module works as expected and we can import quil.expression successfully.

[MarquessV]

cargo msrv is failing, but I'm not sure why. It works locally, both directly on my machine and in a linux docker container using the same toolchain as CI.

[Shadow53]

Looks good! Thanks for finding and fixing this.