Disable scrolling on web by default but provide method in builder to enable it

[rukai]

closes https://github.com/rust-windowing/winit/issues/2116

• [x] Tested on all platforms changed
• [x] Added an entry to CHANGELOG.md if knowledge of this change could be valuable to users
• [x] Updated documentation to reflect any user-facing changes, including notes of platform-specific behavior
• [x] Created or updated an example program if it would help users understand this functionality
• [x] Updated feature matrix, if new features were added or implemented

Tested on firefox on my desktop and firefox on my android phone.

[rukai]

Hmmmm not sure how much it matters but should be tagged web not android