Better detection of string store types on primitive collections (#30920)

Author: ajcvickers

src/EFCore.SqlServer/Storage/Internal/SqlServerTypeMappingSource.cs

@@ -437,16 +437,20 @@ public SqlServerTypeMappingSource(
             return null;
         }
 
-        switch (mappingInfo.StoreTypeNameBase)
+        switch (mappingInfo.StoreTypeNameBase?.ToLowerInvariant())
         {
+            case "nvarchar":
+            case "varchar":
             case "char varying":
             case "char":
             case "character varying":
             case "character":
+            case "nchar":
             case "national char varying":
             case "national character varying":
             case "national character":
-            case "varchar":
+            case "text":
+            case "ntext":
             case null:
                 break;
             default:

test/EFCore.Relational.Tests/Storage/RelationalTypeMapperTestBase.cs

@@ -20,6 +20,7 @@ protected IMutableEntityType CreateEntityType<TEntity>()
         builder.Entity<MyPrecisionType>().Property(e => e.PrecisionOnly).HasPrecision(16);
         builder.Entity<MyPrecisionType>().Property(e => e.PrecisionAndScale).HasPrecision(18, 7);
         builder.Entity<MyTypeWithIndexAttribute>();
+        builder.Entity<MyTypeWithIndexAttributeOnCollection>();
 
         return builder.Model.FindEntityType(typeof(TEntity));
     }
@@ -203,4 +204,11 @@ protected class MyTypeWithIndexAttribute
         public int Id { get; set; }
         public string Name { get; set; }
     }
+
+    [Index(nameof(Ints))]
+    protected class MyTypeWithIndexAttributeOnCollection
+    {
+        public int Id { get; set; }
+        public IEnumerable<int> Ints { get; set; }
+    }
 }