Always download PDF + non HTML page cleanup + enterprise policy clean…

…up (#629)

Adds enterprise policy to always download PDF and sets download dir to
/dev/null
Moves policies to chromium.json and brave.json for clarity
Further cleanup of non-HTML loading path:
- sets downloadResponse when page load is aborted but response is
actually download
- sets firstResponse when first response finishes, but page doesn't
fully load
 - logs that non-HTML pages skip all post-crawl behaviors in one place
 - move page extra delay to separate awaitPageExtraDelay() function, applied for all pages (while post-load delay only applied to HTML pages)

---------
Co-authored-by: Tessa Walsh <[email protected]>

config/policies/brave-default.json → config/policies/brave.json

@@ -2,5 +2,6 @@
     "BraveRewardsDisabled": true,
     "BraveWalletDisabled": true,
     "BraveVPNDisabled": 1,
-    "BraveAIChatEnabled": false
+    "BraveAIChatEnabled": false,
+    "TorDisabled": true
 }

config/policies/lockdown-profilebrowser.json → config/policies/chromium.json

@@ -1,10 +1,11 @@
 {
+    "AlwaysOpenPdfExternally": true,
     "NewTabPageLocation": "about:blank",
     "RestoreOnStartup": 5,
     "IncognitoModeAvailability": 1,
-    "TorDisabled": true,
     "AllowFileSelectionDialogs": false,
     "URLBlocklist": [
         "file://*"
-    ]
+    ],
+    "DownloadDirectory": "/dev/null"
 }