build: remove duplicate devtools sources (#14522)

* build: remove duplicate devtools sources

* build: create separate target for chrome sources

* Move sources that are always depended on by electron,
  starting with security_state_tab_helper.{cc|h}
* Add //component/strings to pak for devtools security tab

* fix: allow specifying type of the added filesystem.

https://chromium-review.googlesource.com/c/chromium/src/+/729250

* fix: do not index excluded folders

https://chromium-review.googlesource.com/c/chromium/src/+/972579

atom/browser/api/atom_api_web_contents.cc

@@ -1455,7 +1455,7 @@ void WebContents::AddWorkSpace(mate::Arguments* args,
     args->ThrowError("path cannot be empty");
     return;
   }
-  DevToolsAddFileSystem(path);
+  DevToolsAddFileSystem(std::string(), path);
 }
 
 void WebContents::RemoveWorkSpace(mate::Arguments* args,