Add Override Equals method to softButtonObject

[JulianKast]

Fixes #1257

This PR is ready for review.

Risk

This PR makes minor API changes.

Testing Plan

• I have verified that I have not introduced new warnings in this PR (or explain why below)
• I have run the unit tests with this PR
• I have tested this PR against Core and verified behavior (if applicable, if not applicable, explain why below).
• I have tested Android, Java SE, and Java EE

Unit Tests

Added testSoftButtonEq() and testSoftButtonStateEq() to SoftButtonManagerTests and testSdlFIleEq() to FileManagerTest

Core Tests

Tested using manticore

Summary

Added a method in SdlFile in android and JavaSE, softButtonObjects, and SoftButtonState that overrides their equals methods. The new equals methods compare the objects variables instead of their memory address.

Enhancements

• Added a method in softButtonObjects that overrides its equals method.
• Added a method in softButtonState that overrides its equals method.
• Added a method in SdlFile that overrides its equals method for android and JavaSE.

CLA

• I have signed the CLA

[codecov]

Codecov Report

Merging #1307 into develop will increase coverage by 0.03%.
The diff coverage is 72.72%.

@@              Coverage Diff              @@
##             develop    #1307      +/-   ##
=============================================
+ Coverage      47.56%   47.60%   +0.03%     
- Complexity      4391     4404      +13     
=============================================
  Files            488      488              
  Lines          23735    23754      +19     
  Branches        2737     2749      +12     
=============================================
+ Hits           11290    11308      +18     
+ Misses         11755    11753       -2     
- Partials         690      693       +3     

Impacted Files	Coverage Δ	Complexity Δ
...rtdevicelink/managers/screen/SoftButtonObject.java	63.33% <63.63%> (+2.57%)	27.00 <6.00> (+7.00)
...artdevicelink/managers/screen/SoftButtonState.java	51.35% <75.00%> (+6.52%)	12.00 <6.00> (+6.00)
...vicelink/managers/screen/choiceset/ChoiceCell.java	87.50% <100.00%> (+3.57%)	26.00 <0.00> (ø)
...smartdevicelink/managers/screen/menu/MenuCell.java	80.28% <100.00%> (+1.40%)	29.00 <0.00> (ø)