Factor out construction of font-related JSON schemas (#15341)

This PR factors out the construction of the font-related JSON schemas,
as they were used in multiple places.

Release Notes:

- N/A

crates/settings/src/settings_store.rs

@@ -17,6 +17,8 @@ use std::{
 };
 use util::{merge_non_null_json_value_into, RangeExt, ResultExt as _};
 
+use crate::SettingsJsonSchemaParams;
+
 /// A value that can be defined as a user setting.
 ///
 /// Settings can be loaded from a combination of multiple JSON files.
@@ -146,12 +148,6 @@ pub struct SettingsLocation<'a> {
     pub path: &'a Path,
 }
 
-pub struct SettingsJsonSchemaParams<'a> {
-    pub staff_mode: bool,
-    pub language_names: &'a [String],
-    pub font_names: &'a [String],
-}
-
 /// A set of strongly-typed setting values defined via multiple JSON files.
 pub struct SettingsStore {
     setting_values: HashMap<TypeId, Box<dyn AnySettingValue>>,