Add "discoveries" chart

android/gradle.properties

assets/translations/en.json

assets/translations/fr.json

fastlane/metadata/android/en-US/changelogs/20.txt

fastlane/metadata/android/fr-FR/changelogs/20.txt

lib/models/discoveries.dart

lib/network/scrobbles_api.dart

lib/ui/screens/main_screen.dart

lib/ui/widgets/charts/custom_bar_chart.dart

lib/ui/widgets/main_screen/counts_by_day_chart.dart

lib/ui/widgets/main_screen/counts_by_hour_chart.dart

lib/ui/widgets/main_screen/discoveries_card.dart

lib/ui/widgets/main_screen/discoveries_chart.dart

lib/ui/widgets/main_screen/discoveries_content.dart

lib/ui/widgets/main_screen/timeline_chart_counts.dart

pubspec.yaml