convert DecryptionFailureTracker to swift + tests

[BillCarsonFr]

Preliminary work for #7767

Converts DecryptionFailureTracker from objective-c to swift to ease future changes.
Also added some tests. I didn't find any existing mock framework, so I modified a bit the code to be easily testable

Pull Request Checklist

• I read the contributing guide
• UI change has been tested on both light and dark themes, in portrait and landscape orientations and on iPhone and iPad simulators
• Accessibility has been taken into account.

• Pull request is based on the develop branch

• Pull request contains a changelog file in ./changelog.d
• You've made a self review of your PR
• Pull request includes screenshots or videos of UI changes
• Pull request includes a sign off

[BillCarsonFr]

Just extracted that protocol to make testing of decryption failure tracker easier

[codecov]

Codecov Report

Attention: Patch coverage is 87.85714% with 17 lines in your changes are missing coverage. Please review.

Project coverage is 12.25%. Comparing base (0b8fb85) to head (56e6653).

Files	Patch %	Lines
...t/Modules/Analytics/DecryptionFailureTracker.swift	88.39%	8 Missing and 5 partials ⚠️
Riot/Modules/Analytics/Analytics.swift	0.00%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #7769      +/-   ##
===========================================
+ Coverage    12.19%   12.25%   +0.06%     
===========================================
  Files         1650     1651       +1     
  Lines       164100   164133      +33     
  Branches     67487    67490       +3     
===========================================
+ Hits         20012    20116     +104     
+ Misses      143420   143346      -74     
- Partials       668      671       +3     

Flag	Coverage Δ
unittests	6.11% <87.85%> (+0.06%)	⬆️

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[Velin92]

LGTM

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud