Add .gitignore (#85017)

packages/flutter_tools/templates/app/winuwp.tmpl/.gitignore

+flutter/ephemeral/
+
+# Visual Studio user-specific files.
+*.suo
+*.user
+*.userosscache
+*.sln.docstates
+
+# Visual Studio build-related files.
+x64/
+x86/
+
+# Visual Studio cache files
+# files ending in .cache can be ignored
+*.[Cc]ache
+# but keep track of directories ending in .cache
+!*.[Cc]ache/

packages/flutter_tools/templates/template_manifest.json

@@ -6,6 +6,7 @@
         "templates/app/pubspec.yaml.tmpl",
         "templates/app/README.md.tmpl",
         "templates/app/test/widget_test.dart.tmpl",
+        "templates/app/winuwp.tmpl/.gitignore",
 
         "templates/app_shared/.gitignore.tmpl",
         "templates/app_shared/.idea/libraries/Dart_SDK.xml.tmpl",