Add copy function and unit tests to StartWorkflowExecutionParameters

[timl3136]

What changed?
Add copy function and unit tests to StartWorkflowExecutionParameters

Why?
Improve unit test coverage

How did you test it?
Unit tests

Potential risks

Release notes

Documentation Changes

[coveralls]

Pull Request Test Coverage Report for Build 2637

Details

• 16 of 16 (100.0%) changed or added relevant lines in 1 file are covered.
• 2 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.08%) to 80.327%

---

Files with Coverage Reduction	New Missed Lines	%
src/main/java/com/uber/cadence/internal/testservice/TestWorkflowMutableStateImpl.java	1	85.33%
src/main/java/com/uber/cadence/internal/common/InternalUtils.java	1	79.61%

Totals
Change from base Build 2635:	0.08%
Covered Lines:	15589
Relevant Lines:	19407

---

💛 - Coveralls