feat: flutter integration tests

[minikin]

Description

• Validation of integration tests across multiple platforms using a single codebase.

Related Issue(s)

#85

Description of Changes

• Add mock UI to run integration tests
• Configure Web, iOS, and Android targets to run integration tests
• Create integration tests for mock UI
• Set up Firebase Test Lab
• Upload test results to GC
• Add CI/CD workflow for Web (run it on each PR)
• Add CI/CD workflow for iOS/Android (run it NIghtly)

Ouf of scope

• 🛠️ [TASK] : Migrate Flutter iOS and Android Integration Tests Workflow to Earthly #130
• 🛠️ [TASK] : Migrate Flutter Web Integration Tests to Earthly #131

Breaking Changes

NONE

Screenshots

Mock UI

Test Labs Results

Videos

Local tests

Web

CleanShot.2023-11-09.at.10.54.18-converted.mp4

iOS

test_ios.mp4

Android

CleanShot.2023-11-09.at.10.24.49-trimmed.mp4

Test Lab

Android

integration_test_results_android_redfin-30-en_GB-portrait_video.mp4

iOS

2023-11-08_17_39_17.606635_CeTi_iphone14pro-16.6-en_GB-portrait_video.mp4

Please confirm the following checks

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in the downstream module

[stevenj]

Looks great.