feat: persistant in-app messages

[Shahroz16]

Gist returns 304 when there is no change in queue status, in Android/OKhttp until we have etag in headers Retrofit doesn't cache and returns the same response. So this adds a workaround where if the response hasn't changed then return the old response for that URL which was returned.

This PR has already passed QA testing.

[github-actions[bot]]

# Sample app builds 📱 Below you will find the list of the latest versions of the sample apps. It's recommended to always download the latest builds of the sample apps to accurately test the pull request. --- * java_layout: `shahroz/in-app-persistant (1698232761)` * kotlin_compose: `shahroz/in-app-persistant (1698232766)`

[codecov[bot]]

Codecov Report

Merging #269 (37ff6fc) into main (c494bb0) will increase coverage by 0.67%. Report is 18 commits behind head on main. The diff coverage is 44.11%.

@@             Coverage Diff              @@
##               main     #269      +/-   ##
============================================
+ Coverage     49.76%   50.44%   +0.67%     
- Complexity      237      249      +12     
============================================
  Files           108      108              
  Lines          2781     2809      +28     
  Branches        364      363       -1     
============================================
+ Hits           1384     1417      +33     
+ Misses         1282     1275       -7     
- Partials        115      117       +2     

Files	Coverage Δ
...customer/messaginginapp/gist/data/model/Message.kt	54.00% <0.00%> (+1.05%)	:arrow_up:
...main/java/io/customer/sdk/queue/QueueRunRequest.kt	98.00% <97.56%> (+7.61%)	:arrow_up:
...stomer/messaginginapp/gist/presentation/GistSdk.kt	13.17% <33.33%> (+13.17%)	:arrow_up:
...ssaginginapp/gist/presentation/GistModalManager.kt	14.70% <0.00%> (+14.70%)	:arrow_up:
...stomer/messaginginapp/gist/data/listeners/Queue.kt	10.57% <30.76%> (+10.57%)	:arrow_up:
...saginginapp/gist/presentation/GistModalActivity.kt	0.00% <0.00%> (ø)
...inginapp/gist/presentation/engine/EngineWebView.kt	0.00% <0.00%> (ø)

... and 1 file with indirect coverage changes

[github-actions[bot]]

Build available to test Version: shahroz-in-app-persistant-SNAPSHOT Repository: https://s01.oss.sonatype.org/content/repositories/snapshots/