feat: add rules to auto convert Awkward types

[ianna]

Here is an example of using from in Python:

>>> import awkward as ak
>>> from juliacall import Main as jl
>>> array = ak.Array([[1.1, 2.2, 3.3], [], [4.4, 5.5]])
>>> jl.AwkwardArray.convert(array)
Julia:
3-element AwkwardArray.ListOffsetArray{SubArray{Int64, 1, PyArray{Int64, 1, true, true, Int64}, Tuple{UnitRange{Int64}}, true}, AwkwardArray.PrimitiveArray{Float64, SubArray{Float64, 1, PyArray{Float64, 1, true, true, Float64}, Tuple{UnitRange{Int64}}, true}, :default}, :default}:
 [1.1, 2.2, 3.3]
 0-element AwkwardArray.PrimitiveArray{Float64, Vector{Float64}, :default}
 [4.4, 5.5]

[codecov]

Codecov Report

Attention: 21 lines in your changes are missing coverage. Please review.

Comparison is base (ea089c2) 72.03% compared to head (009bcaf) 71.66%.
Report is 2 commits behind head on main.

❗ Current head 009bcaf differs from pull request most recent head d6000ab. Consider uploading reports for the commit d6000ab to get more accurate results

Files	Patch %	Lines
ext/AwkwardPythonCallExt/AwkwardPythonCallExt.jl	40.00%	21 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #57      +/-   ##
==========================================
- Coverage   72.03%   71.66%   -0.38%     
==========================================
  Files           4        4              
  Lines        1613     1648      +35     
==========================================
+ Hits         1162     1181      +19     
- Misses        451      467      +16     

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[ianna]

The custom conversion rules define a function to do the conversion. The pyconvert_add_rule function is called to register it.

[ianna]

from Julia docs: if you define a function __init__() in a module, then Julia will call __init__() immediately after the module is loaded (e.g., by import, using, or require) at runtime for the first time (i.e., __init__ is only called once, and only after all statements in the module have been executed). Because it is called after the module is fully imported, any submodules or other imported modules have their __init__ functions called before the __init__ of the enclosing module.