[cjdoris]

Move the Python wrapper implementations embedded in src/JlWrap into matching files under pysrc/juliacall/_jlwrap. Each module uses a method-name dictionary populated by the corresponding Julia initializer, removing the need to interpolate method numbers into Python source.

_jlwrap exports all wrapper types, and juliacall imports them once the native ValueBase type is available. Preserve the public juliacall.*Value identities and read the array buffer method number from its module dictionary. Also move the callback wrapper lambda into Python.

Validation:

• Julia suite: 3,517 passed, 2 broken/skipped.
• Python suite, including notebooks: 21 passed.
• Restored the original juliapkg.json after Python tests.
• git diff --check passed.

[cjdoris]

@oxinabox I think this will fix the issue in #808 - could you try it please? AFAIU the issue is that pythoncall evals some python code with a filename that pytest doesn't class as being user code (because it's in a julia file in some non-python location). This change moves all that python code into the actual juliacall source, so pytest will now classify it correctly.