44aeb0a311
This patch makes it unnecessary for most features to have to override `shouldEnable`. Instead, the Suggest framework will check `enablingPreferences` plus a new property called `additionalEnablingPredicate`. Summary: * Include Nimbus variables in `enablingPreferences` * Add a new property to `SuggestFeature` called `additionalEnablingPredicate` * Make `shouldEnable` call `enablingPreferences` and `additionalEnablingPredicate` * Remove `shouldEnable` implementations on most features Differential Revision: https://phabricator.services.mozilla.com/D235251