Allow for Node Attribute dependencies

[PythonFZ]

This PR allows you to directly depend on other nodes attributes and not only rely on the full Node.

class Node1(Node):
    outs: int = zn.outs()
    
class Node2(Node):
    node_1_outs: int = zn.deps(getdeps(Node1, "outs"))
    # or
    node_1_outs: int = zn.deps(getdeps(Node1.load(name="nodename"), "outs"))
    # or
    node_1_outs: int = zn.deps(getdeps(Node1["nodename"], "outs"))

TODOs

• check type hints for getdeps
• write tests for properties
• update affected_files to include only the required files. This is not possible, because e.g. property dependencies can not be evaluated (easily)
• update documentation (include new load method via getitem)

[codecov]

Codecov Report

Merging #255 (469491d) into main (3fd818b) will increase coverage by 0.20%.
The diff coverage is 77.77%.

@@            Coverage Diff             @@
##             main     #255      +/-   ##
==========================================
+ Coverage   71.42%   71.63%   +0.20%     
==========================================
  Files          25       26       +1     
  Lines        1071     1100      +29     
  Branches      208      211       +3     
==========================================
+ Hits          765      788      +23     
- Misses        283      288       +5     
- Partials       23       24       +1     

Flag	Coverage Δ
unittests	71.63% <77.77%> (+0.20%)	⬆️

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Impacted Files	Coverage Δ
zntrack/zn/__init__.py	82.35% <0.00%> (ø)
zntrack/utils/serializer.py	76.05% <58.33%> (-2.64%)	⬇️
zntrack/zn/dependencies.py	88.23% <88.23%> (ø)
zntrack/__init__.py	100.00% <100.00%> (ø)
zntrack/core/dvcgraph.py	72.10% <100.00%> (+0.19%)	⬆️
zntrack/utils/helpers.py	90.00% <100.00%> (ø)

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