[BEAM-1833] Give transforms more control over the names of their inputs and outputs.

[robertwb]

This does not fully resolve BEAM-1833, but that cleanup will be best done once all runners are portable.

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Post-Commit Tests Status (on master branch)

Lang	SDK	Dataflow	Flink	Samza	Spark	Twister2
Go		---		---		---
Java
Python				---		---
XLang				---		---

Pre-Commit Tests Status (on master branch)

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Portable	---		---	---	---	---

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[codecov]

Codecov Report

Merging #13672 (7e8fa4e) into master (e12a0d8) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master   #13672      +/-   ##
==========================================
+ Coverage   82.73%   82.75%   +0.01%     
==========================================
  Files         466      466              
  Lines       57518    57520       +2     
==========================================
+ Hits        47589    47598       +9     
+ Misses       9929     9922       -7     

Impacted Files	Coverage Δ
sdks/python/apache_beam/dataframe/frames.py	91.98% <100.00%> (ø)
sdks/python/apache_beam/pipeline.py	91.11% <100.00%> (+0.78%)	⬆️
sdks/python/apache_beam/transforms/ptransform.py	93.06% <100.00%> (+0.10%)	⬆️
sdks/python/apache_beam/utils/interactive_utils.py	88.09% <0.00%> (-2.39%)	⬇️
sdks/python/apache_beam/io/iobase.py	84.81% <0.00%> (-0.27%)	⬇️
sdks/python/apache_beam/transforms/util.py	95.84% <0.00%> (+0.17%)	⬆️
...hon/apache_beam/runners/worker/bundle_processor.py	93.83% <0.00%> (+0.38%)	⬆️

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[robertwb]

R: @boyuanzz

[boyuanzz]

Thanks!

[robertwb]

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