Better JS language integration for Pre-Request scripts and Test scripts (#1422)

* Add tern as dependency

* Add build rule to transpile mjs

* Initial implementation of the auto complete engine

* Separate out the tern server code to separate file

* Added extra type defs for tern server

* Boost the pw completion result to the top of the list

* Added acorn and acorn-walk as dependency

* Semantic linting powered by tern

* Fix DeepCode warnings for js-editor

* Remove unused registerLint tern extension

Co-authored-by: Liyas Thomas <liyascthomas@gmail.com>

helpers/terndoc/pw-extras.json

@@ -0,0 +1,51 @@
+{
+  "!name": "pw-extra",
+  "console": {
+    "assert": {
+      "!type": "fn(assertion: bool, text: string)"
+    },
+    "clear": {
+      "!type": "fn()"
+    },
+    "count": {
+      "!type": "fn(label?: string)"
+    },
+    "debug": "console.log",
+    "dir": {
+      "!type": "fn(object: ?)"
+    },
+    "error": {
+      "!type": "fn(...msg: ?)"
+    },
+    "group": {
+      "!type": "fn(label?: string)"
+    },
+    "groupCollapsed": {
+      "!type": "fn(label?: string)"
+    },
+    "groupEnd": {
+      "!type": "fn()"
+    },
+    "info": {
+      "!type": "fn(...msg: ?)"
+    },
+    "log": {
+      "!type": "fn(...msg: ?)"
+    },
+    "table": {
+      "!type": "fn(data: []|?, columns?: [])"
+    },
+    "time": {
+      "!type": "fn(label: string)"
+    },
+    "timeEnd": {
+      "!type": "fn(label: string)"
+    },
+    "trace": {
+      "!type": "fn()"
+    },
+    "warn": {
+      "!type": "fn(...msg: ?)"
+    }
+  }
+}