Harmonize with crate-1.0.0: `ModuleNotFoundError: No module named 'crate.client'`

[amotl]

Problem

After upgrading to crate-1.0.0 (dev), running the testsuite using python -m unittest -vvv trips, not able to find crate.client any longer.

Traceback (most recent call last):
  File "/path/to/lib/python3.12/unittest/loader.py", line 396, in _find_test_path
    module = self._get_module_from_name(name)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/path/to/lib/python3.12/unittest/loader.py", line 339, in _get_module_from_name
    __import__(name)
  File "/path/to/crash/tests/test_sysinfo.py", line 29, in <module>
    from crate.crash.command import CrateShell
  File "/path/to/crash/crate/crash/command.py", line 43, in <module>
    from crate.client import connect
ModuleNotFoundError: No module named 'crate.client'

• Dependencies: Update to crate-1.0.0.dev2 to support final GA testing #446

This is probably coming from the transition to "implicit namespace packages".

• Python: Migrate to use "implicit namespace packages" (PEP 420) crate-python#666

Observations

The problem does not happen at runtime, so we are safe on this side at least.

uv pip install --upgrade "crate>=1.0.0.dev2" crash
$ crash --version
0.31.5

Solution

The crash repository currently manages its fragment of the crate namespace package within a top-level folder. It should probably use the "src layout", like crate-python is also doing it, storing the actual module's source under src/crate/.

The “src layout” deviates from the flat layout by moving the code that is intended to be importable into a subdirectory. This subdirectory is typically named src/, hence “src layout”.

The src layout helps prevent accidental usage of the in-development copy of the code.

-- https://packaging.python.org/en/latest/discussions/src-layout-vs-flat-layout/

Evaluation

In previous times of Python packaging, and when using the previous variants of implementing namespace packages, this detail probably didn't play a relevant role. Now, apparently, it does, and needs a minor refactoring of the directory layout.

/cc @surister, @simonprickett, @kneth

[amotl]

Resolved with GH-448.