Fenix: Create a setting for Pull to refresh

[Timvde]

Why/User Benefit/User Problem

There are multiple people on /r/Firefox who dislike the new feature. It would be nice if there was a way to disable it.

What/Requirements

Create a setting to disable pull to refresh.

Acceptance Criteria (how do I know when I’m done?)

If there's a switch that I can toggle which disables pull to refresh.

[lindongbin]

It's easy to trigger when zooming

[danielzgtg]

On some websites, pull to refresh makes it easy to lose all your work

[Rodze]

It's easy to trigger when zooming

It's easy to trigger doing anything. I don't use Chrome, so I went there to see if this thing exists and it does. And it's still extremely annoying even though the Chrome implementation has already fixed some of the bugs that exist on Firefox (like refreshing when scrolling text input fields).

It should be disabled by default and anyone who wants to live dangerously can turn it on with the setting, which is absolutely necessary.

[cadeyrn]

It is already disabled by default in the latest master build. And for bugs / problems with the current implementation please see #9766. Please differentiate between something unfinished in a Nightly build and the expected end result. Yes, I agree, an option to disable the feature seems like a good idea. But the option should be provided for people who don't like the feature, not because of bugs in the _current implementation of a Nightly build_. Two different stories. ;-)