feat(debugger): debug Flutter apps through the Flutter debug adapter (#1474)

Dart projects that depend on the Flutter SDK were debugged through
`dart debug_adapter`, which cannot start a program importing dart:ui and has no
hot reload. A session now uses `flutter debug_adapter` when the program's or the
working directory's pubspec.yaml depends on the Flutter SDK, or when an attach
configuration asks for it (add-to-app: vm-service-uri and device map to the
adapter's attach arguments). Hot Reload and Hot Restart are sent over DAP and
appear in the toolbar of Dart sessions. Dart files also get a debug configuration.

Co-authored-by: payailk <[email protected]>

src/platform/locales/text/zh.json

@@ -162,6 +162,10 @@
   "Fixup…": "修补提交…",
   "Step Over": "单步跳过",
   "Step Out": "单步跳出",
+  "Hot Reload": "热重载",
+  "Hot Restart": "热重启",
+  "Flutter: inject the changed sources into the running app": "Flutter：将改动后的源码注入正在运行的应用",
+  "Flutter: restart the app, discarding its state": "Flutter：重启应用，丢弃当前状态",
   "Zoom In": "放大",
   "Zoom Out": "缩小",
   "Actual Size": "实际大小",