Fix Enum.from_value? for flag enum with non Int32 base type (#10303)

spec/std/enum_spec.cr

@@ -25,6 +25,13 @@ enum SpecEnumFlags
   Three
 end
 
+@[Flags]
+enum SpecEnumFlags8 : Int8
+  One
+  Two
+  Three
+end
+
 @[Flags]
 private enum PrivateFlagsEnum
   FOO
@@ -167,6 +174,7 @@ describe Enum do
       SpecEnumFlags.from_value?(2).should eq(SpecEnumFlags::Two)
       SpecEnumFlags.from_value?(3).should eq(SpecEnumFlags::One | SpecEnumFlags::Two)
       SpecEnumFlags.from_value?(8).should be_nil
+      SpecEnumFlags8.from_value?(1_i8).should eq(SpecEnumFlags8::One)
     end
   end
 

src/enum.cr

@@ -357,7 +357,7 @@ struct Enum
     {% if @type.annotation(Flags) %}
       all_mask = {{@type}}::All.value
       return if all_mask & value != value
-      return new(value.to_i)
+      return new(all_mask.class.new(value))
     {% else %}
       {% for member in @type.constants %}
         return new({{@type.constant(member)}}) if {{@type.constant(member)}} == value