Maintenance & fixes

[guidezpl]

Description

Maintenance

• Remove Firebase files to avoid crash reports from forks and update Android and iOS Firebase app ID
• Fix Android crash due to missing crashlytics plugin
• Regenerate android/app/src/main/AndroidManifest.xml
• Update android/crane/build.gradle
• Update releasing instructions
• Remove Fastlane production lane for deploying directly to production (use beta and promote_to_production instead)
• Regenerate Fastlane documentation
• Remove macOS from Firebase config
• Update Runner.xcodeproj/project.pbxproj and pubspec files

Fixes

• Disable deferred components (Android app crashes when trying to load Deferred Component Crane #926)
• Respect brightness of web for the background
• Adjust the logo transform animation on web
• Fix Android splash screen backgroundColor (Fixes Android Splash Screen Background #930)

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Note: Please find the development and releasing instructions at https://github.com/flutter/gallery#development

[JoseAlba]

LGTM

[clocksmith]

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[clocksmith]

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