Reorganize files in project

Example/Example.xcodeproj/project.pbxproj

Example/example-app-icon/.gitignore

...ftpm/xcode/xcshareddata/xcschemes/ExampleAppIcon.xcscheme

...e/xcshareddata/xcschemes/example-app-icon-export.xcscheme

Example/example-app-icon/Package.swift

...mple-app-icon/Sources/ExampleAppIcon/ExampleAppIcon.swift

.../example-app-icon/Sources/ExampleAppIconExport/main.swift

Example/example-app/.gitignore

....swiftpm/xcode/xcshareddata/xcschemes/AppFeature.xcscheme

...wiftpm/xcode/xcshareddata/xcschemes/ErrorFeature.xcscheme

...ftpm/xcode/xcshareddata/xcschemes/LandingFeature.xcscheme

...ftpm/xcode/xcshareddata/xcschemes/SessionFeature.xcscheme

...swiftpm/xcode/xcshareddata/xcschemes/example-app.xcscheme

Example/example-app/Package.swift

Example/example-app/Sources/AppFeature/App.swift

Example/example-app/Sources/AppFeature/AppFeature.swift

Example/example-app/Sources/AppFeature/AppView.swift

...ple-app/Sources/AppFeature/PasswordStorage+Keychain.swift

Example/example-app/Sources/ErrorFeature/ErrorFeature.swift

Example/example-app/Sources/ErrorFeature/ErrorView.swift