Required settings by language

[jamesmaa]

Change settings based on language selected. #1542 is an example.

Settings can be similar to the form as #1328 with modifications. Namely I believe only idempotent operations should be allowed with Modifications. Secondly I believe there should be an optional hideSetting field that determines whether a setting should be hidden after setting.

Adding a new required setting to a language should only involve editing a single json file. All the CSS for hiding the setting should be programmatically done.

Also need to fold #1542 into the required settings framework

[jamesmaa]

Kuuuube mentioned not wanting to override the setting values in case profiles get copied and the previous user's selection gets erased

Some directions we can go

Implementation 1: override the settings value would be the simplest implementation but has the drawbacks of changing a user's settings value without notifying them. This could technically be hedged by requiring all settings to have "required | recommended | null" value or by notifying the user which values have changed.
Implementation 2: store the required setting separately and resolve the final setting value in setting-controller.js. This preserves "memory" by not changing the user-set value but the downside is that the user setting value in the settings page would not reflect the true value (and instrumenting the settings page to reflect this is a ton of work)

I'm leaning towards implementation 1 with a notification on which settings have changed. Thoughts @Kuuuube?