refactor(i18n): pull tabs and database tab names into hellionstrings

Both tab classes were the last two settings tabs still pulling their
display name from the upstream Language resource bundle. Move them
into HellionStrings so all eight settings tabs share one i18n source.
The unused Language.Options_*_Tab keys stay around for backwards
compat with cherry-picked upstream tabs.

ChatTwo/Ui/SettingsTabs/Database.cs

@@ -16,7 +16,7 @@ internal sealed class Database : ISettingsTab
     private Plugin Plugin { get; }
     private Configuration Mutable { get; }
 
-    public string Name => Language.Options_Database_Tab + "###tabs-database";
+    public string Name => HellionStrings.Settings_Tab_Database + "###tabs-database";
 
     internal Database(Plugin plugin, Configuration mutable)
     {

ChatTwo/Ui/SettingsTabs/Tabs.cs

@@ -13,7 +13,7 @@ internal sealed class Tabs : ISettingsTab
     private Plugin Plugin { get; }
     private Configuration Mutable { get; }
 
-    public string Name => Language.Options_Tabs_Tab + "###tabs-tabs";
+    public string Name => HellionStrings.Settings_Tab_Tabs + "###tabs-tabs";
 
     private int ToOpen = -2;