fmt: fix bug that vfmt removes emmbeded struct in struct decl (#8775)

vlib/v/fmt/fmt.v

@@ -643,7 +643,7 @@ pub fn (mut f Fmt) struct_decl(node ast.StructDecl) {
 		f.write(gtypes)
 		f.write('>')
 	}
-	if node.fields.len == 0 && node.pos.line_nr == node.pos.last_line {
+	if node.fields.len == 0 && node.embeds.len == 0 && node.pos.line_nr == node.pos.last_line {
 		f.writeln(' {}\n')
 		return
 	}

vlib/v/fmt/tests/struct_embed_keep.vv

@@ -10,3 +10,8 @@ struct Bar {
 	y int
 	z string
 }
+
+struct Baz {
+	Foo
+	Test
+}

vlib/v/fmt/tests/structs_expected.vv

@@ -25,6 +25,10 @@ pub mut:
 	pub_mut_field string
 }
 
+struct Bar {
+	Foo
+}
+
 fn new_user() User {
 	return User{
 		name: 'Serious Sam'

vlib/v/fmt/tests/structs_input.vv

@@ -25,6 +25,8 @@ struct Foo {
 	pub_mut_field string
 }
 
+struct Bar { Foo }
+
 fn new_user()
 User
 {