feat: add preset event app end

[zhu-xiaowei]

• PR title and description conform to Pull Request guidelines.

Description of changes:

1. add preset event app end

How did you test these changes?
Added test case for _app_end event.

Documentation update required?

• No
• Yes (Please include a PR link for the documentation update)

General Checklist

• Added Unit Tests

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

Patch coverage: 94.59% and project coverage change: +0.55% 🎉

Comparison is base (48157d9) 86.04% compared to head (3044145) 86.59%.
Report is 4 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main      #35      +/-   ##
============================================
+ Coverage     86.04%   86.59%   +0.55%     
- Complexity      378      393      +15     
============================================
  Files            39       39              
  Lines          1383     1425      +42     
  Branches        121      125       +4     
============================================
+ Hits           1190     1234      +44     
+ Misses          122      116       -6     
- Partials         71       75       +4     

Files Changed	Coverage Δ
...aws/solution/clickstream/AWSClickstreamPlugin.java	83.52% <ø> (+2.63%)	⬆️
...oftware/aws/solution/clickstream/client/Event.java	100.00% <ø> (ø)
...solution/clickstream/client/ScreenRefererTool.java	84.21% <62.50%> (-15.79%)	⬇️
...ution/clickstream/client/util/PreferencesUtil.java	92.77% <66.66%> (+2.52%)	⬆️
...clickstream/AWSClickstreamPluginConfiguration.java	100.00% <100.00%> (+4.87%)	⬆️
...solution/clickstream/ActivityLifecycleManager.java	97.91% <100.00%> (+0.41%)	⬆️
...olution/clickstream/ClickstreamManagerFactory.java	100.00% <100.00%> (ø)
...tion/clickstream/client/AutoRecordEventClient.java	99.09% <100.00%> (-0.91%)	⬇️
...n/clickstream/client/ClickstreamConfiguration.java	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.