Implement get_pcg_series_parallel_decomposition

[lockshaw]

Description of changes:

• Implement get_pcg_series_parallel_decomposition
• Move initializers from TensorAttrs to WeightAttrs
• Remove ParamSync for now
• Use shape inference in add_layer functions for ComputationGraph and ParallelComputationGraph
• Add a TensorShape field in InputAttrs, forcing all InputAttrs to be non-parallelized for now
• Implement default initializers to match pytorch for a number of layers

Related Issues:

Linked Issues:

• Issue #

Issues closed by this PR:

• Closes Add weight handling for SP decomposition of PCGs #1500

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This change is 

[codecov]

Codecov Report

Attention: Patch coverage is 70.41885% with 226 lines in your changes missing coverage. Please review.

Project coverage is 62.90%. Comparing base (e9a1af7) to head (3d9dee4).

Files with missing lines	Patch %	Lines
lib/op-attrs/src/op-attrs/shape_inference.cc	74.16%	54 Missing ⚠️
...el_computation_graph/parallel_computation_graph.cc	53.33%	28 Missing ⚠️
lib/op-attrs/src/op-attrs/initializer_attrs.cc	0.00%	25 Missing ⚠️
lib/local-execution/src/local_cost_estimator.cc	0.00%	14 Missing ⚠️
lib/op-attrs/src/op-attrs/ops/batch_norm.cc	47.61%	11 Missing ⚠️
lib/op-attrs/src/op-attrs/ops/repartition.cc	0.00%	11 Missing ⚠️
lib/op-attrs/src/op-attrs/ops/attention.cc	83.05%	10 Missing ⚠️
lib/op-attrs/src/op-attrs/ops/combine.cc	0.00%	10 Missing ⚠️
lib/op-attrs/src/op-attrs/ops/reduction.cc	0.00%	10 Missing ⚠️
lib/op-attrs/src/op-attrs/ops/replicate.cc	0.00%	10 Missing ⚠️
... and 13 more

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1598      +/-   ##
==========================================
+ Coverage   62.86%   62.90%   +0.04%     
==========================================
  Files         632      635       +3     
  Lines       14804    15201     +397     
==========================================
+ Hits         9306     9562     +256     
- Misses       5498     5639     +141     

Flag	Coverage Δ
unittests	62.90% <70.41%> (+0.04%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...computation_graph_series_parallel_decomposition.cc	100.00% <100.00%> (ø)
...allel/pcg/get_pcg_series_parallel_decomposition.cc	100.00% <100.00%> (+100.00%)	⬆️
lib/local-execution/src/local_slots_backing.cc	83.16% <100.00%> (ø)
lib/local-execution/src/ops/batch_matmul.cc	0.00% <ø> (ø)
lib/local-execution/src/ops/concat.cc	0.00% <ø> (ø)
lib/local-execution/src/ops/conv_2d.cc	0.00% <ø> (ø)
lib/local-execution/src/ops/dropout.cc	0.00% <ø> (ø)
lib/local-execution/src/ops/element_binary.cc	0.00% <ø> (ø)
lib/local-execution/src/ops/element_unary.cc	0.00% <ø> (ø)
lib/local-execution/src/ops/flat.cc	0.00% <ø> (ø)
... and 50 more

... and 5 files with indirect coverage changes