Disable motion sensors on desktop

[pes10k]

Test plan

See brave/brave-core#2802

Description

Currently Brave enables the motion sensor APIs by default

Brave blocks motion sensors on Android by default currently (https://github.com/brave/browser-android-tabs/issues/1669). Would be good to disable on desktop too by default. Most of the time it'll be a no-op, but would be relevant on some systems (e.g. tablets).

Low web compat risk since most other browsers don't support: https://caniuse.com/#search=sensor

[fmarier]

Looks like this is a trivial fix: https://github.com/bromite/bromite/blob/master/build/patches/disable-sensors-access-site-setting-by-default.patch

See bromite/bromite#319.