Disable sticky key while in panel.

It doesn't make sense to intercept ordinary commands while in the panel; this will help with the i-search experience and the possibility of implementing type to find commands.

Also, rebind i-search to search+ctrl+f (without sticky) and ctrl+f (with sticky). This change is needed because we don't eat key events containing ctrl only without sticky mode on. Ctrl+F causes both regular find and ChromeVox find to pop up (without sticky mode).

TEST=with sticky mode on, use i-search and menus. Do the same without sticky key.
Observe sticky key gets retained (state) when exiting and gets turned off while in panel.

Review URL: https://codereview.chromium.org/1819433002

Cr-Commit-Position: refs/heads/master@{#382033}

chrome/browser/resources/chromeos/chromevox/chromevox/background/keymaps/next_keymap.json

@@ -496,6 +496,7 @@
     {
       "command": "toggleSearchWidget",
       "sequence": {
+        "cvoxModifier": true,
         "keys": {
           "keyCode": [70],
           "ctrlKey": [true]

chrome/browser/resources/chromeos/chromevox/cvox2/background/panel.js

@@ -550,3 +550,12 @@ Panel.closeMenusAndRestoreFocus = function() {
 window.addEventListener('load', function() {
   Panel.init();
 }, false);
+
+window.addEventListener('hashchange', function() {
+  if (location.hash == '#fullscreen' || location.hash == '#focus') {
+    this.originalStickyState_ = cvox.ChromeVox.isStickyPrefOn;
+    cvox.ChromeVox.isStickyPrefOn = false;
+  } else {
+    cvox.ChromeVox.isStickyPrefOn = this.originalStickyState_;
+  }
+}, false);