Move dart_debugger into tonic and use it in mojo dart controller

mojo/dart/embedder/BUILD.gn

Index: mojo/dart/embedder/BUILD.gn
diff --git a/mojo/dart/embedder/BUILD.gn b/mojo/dart/embedder/BUILD.gn
index 4147608ec73b28374c859648bb959e8193bcd6fb..1fd8a47f13d76e9f3109e24d9e24c63fbb1d1d2b 100644
--- a/mojo/dart/embedder/BUILD.gn
+++ b/mojo/dart/embedder/BUILD.gn
@@ -16,14 +16,11 @@ source_set("dart_controller_no_snapshot") {
     "common.h",
     "dart_controller.cc",
     "dart_controller.h",
-    "dart_debugger.cc",
-    "dart_debugger.h",
     "io/internet_address.h",
     "mojo_io_natives.cc",
     "mojo_io_natives.h",
     "mojo_natives.cc",
     "mojo_natives.h",
-    "monitor.h",
     "vmservice.cc",
     "vmservice.h",
   ]
@@ -56,8 +53,6 @@ source_set("dart_controller_no_snapshot") {
   } else {
     defines += [ "NDEBUG" ]
   }
-
-  include_dirs = [ "//dart/runtime" ]
 }
 
 dart_embedder_resources("generate_dart_embedder_patch_resources_cc") {