add brave://adblock tests to manual passes

[LaurenWags]

We should add some tests for brave://adblock (brave://settings/shields/filters) to our manual passes to ensure this page works as expected with major Chromium bumps.

[LaurenWags]

@antonok-edm was discussing this addition to our manual passes, @rebron suggested that you might have some good ideas for this. Thanks!

[antonok-edm]

1. Visit brave://settings/shields/filters
2. Type "cookie" into the "Filter lists" search box, and verify that the list is filtered down to just the Easylist-Cookie List - Filter Obtrusive Cookie Notices
3. Enable the cookie list
4. Refresh the page
5. Expand the regional filter lists and verify that the cookie list is still enabled
6. Enter https://raw.githubusercontent.com/ryanbr/fanboy-adblock/master/fanboy-antifonts.txt into Enter filter list URL and press Add
7. Ensure that the Custom lists table appears, with the newly added entry; Last updated should be now (e.g. 0 seconds ago)
8. Refresh the page after a few seconds and ensure that the Last updated time reflects the time that has passed
9. Use the dropdown next to the entry and verify that all options (Update now, View source, Unsubscribe) are shown
10. Pressing the Update now button should update the timestamp appropriately
11. View source should open the text of the filter list
12. Unsubscribe should delete the entry from the list and hide the table once again
13. The Create custom filters section should be visible with a text box and Save changes button
14. Adding text to the box, pressing Save changes, and refreshing the page should result in the same text appearing in the box after the reload

[kjozwiak]

1. Visit brave://settings/shields/filters
2. Type "cookie" into the "Filter lists" search box, and verify that the list is filtered down to just the Easylist-Cookie List - Filter Obtrusive Cookie Notices
3. Enable the cookie list
4. Refresh the page
5. Expand the regional filter lists and verify that the cookie list is still enabled
6. Enter https://raw.githubusercontent.com/ryanbr/fanboy-adblock/master/fanboy-antifonts.txt into Enter filter list URL and press Add
7. Ensure that the Custom lists table appears, with the newly added entry; Last updated should be now (e.g. 0 seconds ago)
8. Refresh the page after a few seconds and ensure that the Last updated time reflects the time that has passed
9. Use the dropdown next to the entry and verify that all options (Update now, View source, Unsubscribe) are shown
10. Pressing the Update now button should update the timestamp appropriately
11. View source should open the text of the filter list
12. Unsubscribe should delete the entry from the list and hide the table once again
13. The Create custom filters section should be visible with a text box and Save changes button
14. Adding text to the box, pressing Save changes, and refreshing the page should result in the same text appearing in the box after the reload

@antonok-edm we'll basically want to do something similar on Android. It will be a bit different as Android doesn't have brave://settings/shields/filters and still uses the older brave://adblock views. Thoughts on basically using the same thing as https://github.com/brave/qa-resources/pull/510/files just removing the parts that are not applicable to Android at this time?

We'll also want to add a few upgrade cases for every platform as per #510 (review).

[LaurenWags]

@kjozwiak opened #511 for Android so it doesn't hold up the desktop changes.