* inline call to `SettingsStore.isEnabled`
* Remove confusing `SettingsStore.isEnabled`
This was basically the same as `SettingsStore.canSetValue` only more confusing,
so let's get rid of it.
* Add `configDisablesSetting` value for Settings
The current magic where this only works for features (but not beta features!)
is, well, magical. And I need more flexibility here.
* Remove redundant levels constant `LEVELS_FEATURE`
I don't know if this was ever intended to have different semantics to
`LEVELS_DEVICE_ONLY_SETTINGS_WITH_CONFIG`, but if it was, those semantics
shuold have been written down. They now seem to be used entirely
interchangably.
* Apply `strictNullChecks` to `src/components/views/room_settings/*`
* Restore tsconfig.json
* Conform more code to `strictNullChecks`
* Iterate
* Update matrix-widget-api
* Conform more code to `strictNullChecks`
