Added more tests for nosql_execution_stor_util.go

[agautam478]

What changed?
Added more unit tests for PrepareUpdateWorkflowExecutionRequestWithMapsAndEventBuffer and a boiler plate along with 3 tests for all the PrepareTasksWorkflow methods since their return type is different.

Why?
As a par of the code cov inititative.

How did you test it?

Potential risks

Release notes

Documentation Changes

[codecov]

Codecov Report

Merging #5752 (e57a2bf) into master (b2db40e) will increase coverage by 0.01%.
The diff coverage is n/a.

Additional details and impacted files

see 7 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b2db40e...e57a2bf. Read the comment docs.

[coveralls]

Pull Request Test Coverage Report for Build 018e1a66-b882-4ae7-8917-1db683047b88

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 63 unchanged lines in 17 files lost coverage.
• Overall coverage increased (+0.01%) to 63.946%

---

Files with Coverage Reduction	New Missed Lines	%
common/task/weighted_round_robin_task_scheduler.go	1	89.05%
common/task/parallel_task_processor.go	2	93.06%
service/history/task/timer_task_executor_base.go	2	78.38%
common/task/fifo_task_scheduler.go	2	83.51%
service/matching/db.go	2	73.23%
service/history/task/transfer_active_task_executor.go	2	72.38%
service/history/execution/mutable_state_builder.go	2	69.7%
common/persistence/sql/sqlplugin/mysql/db.go	2	79.49%
common/persistence/sql/sqlplugin/mysql/task.go	2	73.68%
service/history/execution/mutable_state_util.go	2	78.48%

Totals
Change from base Build 018e1a62-e176-4694-96a7-76fb6838f9f7:	0.01%
Covered Lines:	93744
Relevant Lines:	146599

---

💛 - Coveralls