Parse default device with Device.fromName

[zachgk]

This makes the names "" and null return the default device (with potentially
specified engine) instead of CPU.

[codecov-commenter]

Codecov Report

Merging #1529 (8b18f00) into master (bb5073f) will decrease coverage by 1.38%.
The diff coverage is 50.07%.

@@             Coverage Diff              @@
##             master    #1529      +/-   ##
============================================
- Coverage     72.08%   70.70%   -1.39%     
- Complexity     5126     5350     +224     
============================================
  Files           473      500      +27     
  Lines         21970    23370    +1400     
  Branches       2351     2552     +201     
============================================
+ Hits          15838    16523     +685     
- Misses         4925     5565     +640     
- Partials       1207     1282      +75     

Impacted Files	Coverage Δ
api/src/main/java/ai/djl/modality/cv/Image.java	69.23% <ø> (-4.11%)	⬇️
...i/djl/modality/cv/translator/BigGANTranslator.java	21.42% <ø> (-5.24%)	⬇️
...odality/cv/translator/BigGANTranslatorFactory.java	33.33% <0.00%> (+8.33%)	⬆️
...nslator/InstanceSegmentationTranslatorFactory.java	14.28% <0.00%> (-3.90%)	⬇️
.../modality/cv/translator/YoloTranslatorFactory.java	8.33% <0.00%> (-1.67%)	⬇️
...i/djl/modality/cv/translator/YoloV5Translator.java	5.69% <0.00%> (ø)
...odality/cv/translator/YoloV5TranslatorFactory.java	8.33% <0.00%> (-1.67%)	⬇️
...pi/src/main/java/ai/djl/ndarray/BytesSupplier.java	54.54% <0.00%> (-12.13%)	⬇️
...pi/src/main/java/ai/djl/repository/Repository.java	83.33% <ø> (ø)
...l/training/loss/SigmoidBinaryCrossEntropyLoss.java	64.00% <0.00%> (ø)
... and 198 more

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