feat: Potentially allow for overriding of client-side feature flags

[SoCuul]

• Appears to be a Key/Value store that utilizes Meta's MobileConfig infrastructure to deploy app config settings per-account.
• The default config dictionary can be found in FBMobileConfigStartupConfigs under the configValues property.
• Potentially could swizzle mobileconfigimpl methods to return certain values for keys manually set by a user.