Add enable/disable currency settings under localization

[brent-hoover]

Since the drop-down, just a few currencies are disabled by default, but we actually a support a ton of currencies, so shop operators should be able to configure which ones they want to support.

[kieckhafer]

Language and currency dropdown should not show if only one of the respective options is active. Currency should replicate language dropdown functionality.

[rymorgan]

We can add a component like the one from: #1797

[rymorgan]

Let's use the same kind of sidebar design we're using for localization.