Replace ONNX with BaseOnnx

[DrChainsaw]

Wip until BaseOnnx is registered

[codecov-io]

Codecov Report

Merging #24 (78d1b9b) into master (f694977) will increase coverage by 1.51%.
The diff coverage is 92.26%.

@@            Coverage Diff             @@
##           master      #24      +/-   ##
==========================================
+ Coverage   91.67%   93.19%   +1.51%     
==========================================
  Files          12       14       +2     
  Lines         709      764      +55     
==========================================
+ Hits          650      712      +62     
+ Misses         59       52       -7     

Impacted Files	Coverage Δ
src/ONNXmutable.jl	100.00% <ø> (ø)
src/deserialize/combine.jl	87.50% <82.60%> (ø)
src/baseonnx/write.jl	82.75% <82.75%> (ø)
src/deserialize/deserialize.jl	95.08% <88.23%> (+2.32%)	⬆️
src/baseonnx/read.jl	90.90% <90.90%> (ø)
src/deserialize/graphbuilder.jl	97.77% <97.56%> (+9.77%)	⬆️
src/baseonnx/BaseOnnx.jl	100.00% <100.00%> (ø)
src/deserialize/ops.jl	96.87% <100.00%> (ø)
src/serialize/serialize.jl	98.03% <100.00%> (+1.47%)	⬆️
src/validate.jl	100.00% <100.00%> (ø)
... and 4 more

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