[flytepropeller] Add Tests in v1alpha.go including array_test.go, branch_test.go, error_test.go, and iface_test.go with 0.13% Coverage Improvment

[Future-Outlier]

TL;DR

Please take a look at the line I change the package from v1alpha1_test to v1alpha1.
I really think it is unnecessary to use a new package, thanks a lot!

https://github.com/flyteorg/flyte/pull/4234/files#diff-e0b8581c1dadc5bdd862a6388d98c81d652943ef1f46c7eeb18d14f6665b7fabR1

Tracking issue

Fixes #4209

Describe your changes

• I updated the documentation accordingly.
• All new and existing tests passed.
• All commits are signed-off.

Screenshots

before

after

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (0fc2ab0) 59.59% compared to head (a14ebd3) 60.23%.

❗ Current head a14ebd3 differs from pull request most recent head ae67c87. Consider uploading reports for the commit ae67c87 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4234      +/-   ##
==========================================
+ Coverage   59.59%   60.23%   +0.64%     
==========================================
  Files         632      562      -70     
  Lines       53628    40297   -13331     
==========================================
- Hits        31960    24274    -7686     
+ Misses      19147    13669    -5478     
+ Partials     2521     2354     -167     

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[Future-Outlier]

@pingsutw I think it is able to be approved and merged, please take a look, thanks a lot