HTML lang setting and Head tags for POS and Crowdfund public pages (#6229)

* HTML lang setting and Head tags for POS and Crowdfund public pages

* updates #6229

* updates 6229

* resolve conflict

* updated according to Nicolas' recommendations

* updates #6229

* Add RawMeta method in safe.cs

* ...

* resolve conflicts

* resolve conflict

* resolve conflicts

* Updates as Nicolas request

* updates

---------

Co-authored-by: d11n <mail@dennisreimann.de>

BTCPayServer/Services/Apps/CrowdfundSettings.cs

@@ -1,13 +1,22 @@
 using System;
 using BTCPayServer.JsonConverters;
 using Newtonsoft.Json;
+using System.Globalization;
+using System.Linq;
 
 namespace BTCPayServer.Services.Apps
 {
     public class CrowdfundSettings
     {
+        public CrowdfundSettings()
+        {
+            Language = "en";
+        }
+
         public string Title { get; set; }
         public string Description { get; set; }
+        public string Language { get; set; }
+        public string HtmlMetaTags{ get; set; }
         public bool Enabled { get; set; } = true;
         public DateTime? StartDate { get; set; }
         public DateTime? EndDate { get; set; }

BTCPayServer/Services/Apps/PointOfSaleSettings.cs

@@ -8,6 +8,7 @@ namespace BTCPayServer.Services.Apps
         public PointOfSaleSettings()
         {
             Title = "Tea shop";
+            Language = "en";
             Template = AppService.SerializeTemplate([
                 new AppItem
                 {
@@ -99,6 +100,8 @@ namespace BTCPayServer.Services.Apps
         public string CustomTipText { get; set; } = CUSTOM_TIP_TEXT_DEF;
         public static readonly int[] CUSTOM_TIP_PERCENTAGES_DEF = { 15, 18, 20 };
         public int[] CustomTipPercentages { get; set; } = CUSTOM_TIP_PERCENTAGES_DEF;
+        public string Language { get; set; }
+        public string HtmlMetaTags{ get; set; }
         public string Description { get; set; }
         public string NotificationUrl { get; set; }
         public string RedirectUrl { get; set; }