Save backup refactor

[ham1]

Further refactoring for readability to createBackupFile and other minor improvements.

Description

Refactoring createBackupFile and minor tidy up of surrounding code.
I've got a bit carried away but tried to commit often so that at least some of the changes can be easily reviewed and applied.

Motivation and Context

The aim is to improve readability and thus make fixing, testing and improving easier.

How Has This Been Tested?

Manually with both backup settings set. Unit testing is still not very easy.

Screenshots (if appropriate):

Types of changes

• Code improvement

Checklist:

• My code follows the code style of this project.
• I have updated the documentation accordingly.

[codecov-io]

Codecov Report

Merging #324 into trunk will increase coverage by <.01%.
The diff coverage is 0%.

@@             Coverage Diff              @@
##              trunk     #324      +/-   ##
============================================
+ Coverage     57.75%   57.75%   +<.01%     
- Complexity     9913     9915       +2     
============================================
  Files          1139     1139              
  Lines         73051    73050       -1     
  Branches       7303     7300       -3     
============================================
+ Hits          42187    42188       +1     
+ Misses        28392    28390       -2     
  Partials       2472     2472

Impacted Files	Coverage Δ	Complexity Δ
src/core/org/apache/jmeter/gui/action/Save.java	13.25% <0%> (+0.07%)	4 <0> (ø)	⬇️
...ocol/jms/org/apache/jmeter/protocol/jms/Utils.java	54.83% <0%> (-2.16%)	15% <0%> (ø)
...apache/jmeter/extractor/TestBoundaryExtractor.java	97.88% <0%> (ø)	17% <0%> (ø)	⬇️
...c/core/org/apache/jmeter/reporters/Summariser.java	86.15% <0%> (+0.76%)	19% <0%> (+1%)	⬆️
...s/org/apache/jmeter/timers/PoissonRandomTimer.java	78.37% <0%> (+5.4%)	10% <0%> (+1%)	⬆️

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[pmouawad]

Thanks @ham1 ,
Could you review my commit as your PR had a conflict after merging of Workbench before it.

I think I didn't miss anything but another eye is welcome.
Regards

[ham1]

@pmouawad Thank you for committing my changes - in future I'm happy to rebase and fix merge issues so you don't have to :) (just let me know via comment or email)

There were only a few minor things:

• formatting of streams api code - they seem to be mostly on one line, whereas I think they read much better when split, (perhaps this is the eclipse formatter?)
• some extra whitespace was added (maybe eclipse settings?)
• I question the JavaDoc on the private methods - it didn't seem to help, I had hoped the method name was sufficient - is there a reason it was added?
• formatting of JavaDoc comments, I think we should agree on a format and make sure it's updated in the style guide on the wiki as we currently have a mix and it would be good to agree to prevent further inconsistency (the location of the description of the param, same or new line)

What's the best way for me to provide these changes? Force push to this PR, new PR, email patch file?

Thanks