UI json edit test (#5705)

* add new codemirror helpers

* adding json helpers to the secret pages

* mark the edit button / link as the edit element instead of the json toggle

* add acceptance tests for JSON editing

ui/tests/pages/helpers/codemirror.js

@@ -0,0 +1,34 @@
+import getCodeMirrorInstance from 'vault/tests/helpers/codemirror';
+// Like fillable, but for the CodeMirror editor
+//
+// Usage: fillIn: codeFillable('[data-test-editor]')
+//        Page.fillIn(code);
+export function codeFillable(selector) {
+  return {
+    isDescriptor: true,
+
+    get() {
+      return function(context, code) {
+        const cm = getCodeMirrorInstance(context, selector);
+        cm.setValue(code);
+        return this;
+      };
+    },
+  };
+}
+
+// Like text, but for the CodeMirror editor
+//
+// Usage: content: code('[data-test-editor]')
+//        Page.code(); // some = [ 'string', 'of', 'code' ]
+export function code(selector) {
+  return {
+    isDescriptor: true,
+    get() {
+      return function(context) {
+        const cm = getCodeMirrorInstance(context, selector);
+        return cm.getValue();
+      };
+    },
+  };
+}