parser: check struct embed with wrong position (#19245)

vlib/v/fmt/tests/structs_input.vv

@@ -8,8 +8,8 @@ struct User {
 }
 
 struct FamousUser {
-pub:
 	User
+pub:
 	aka string
 }
 

vlib/v/parser/struct.v

@@ -197,7 +197,7 @@ fn (mut p Parser) struct_decl(is_anon bool) ast.StructDecl {
 				&& (p.peek_tok.line_nr != p.tok.line_nr || p.peek_tok.kind !in [.name, .amp])
 				&& (p.peek_tok.kind != .lsbr || p.peek_token(2).kind != .rsbr))
 				|| p.peek_tok.kind == .dot) && language == .v && p.peek_tok.kind != .key_fn
-			is_on_top := ast_fields.len == 0 && !(is_field_mut || is_field_global)
+			is_on_top := ast_fields.len == 0 && !(is_field_pub || is_field_mut || is_field_global)
 			mut field_name := ''
 			mut typ := ast.Type(0)
 			mut type_pos := token.Pos{}

vlib/v/parser/tests/struct_embed_wrong_pos_in_pub_err.out

@@ -0,0 +1,7 @@
+vlib/v/parser/tests/struct_embed_wrong_pos_in_pub_err.vv:6:5: error: struct embedding must be declared at the beginning of the struct body
+    4 | pub struct ThreadSafeLog {
+    5 | pub:
+    6 |     Log
+      |     ~~~
+    7 | pub mut:
+    8 |     mu Xyz

vlib/v/parser/tests/struct_embed_wrong_pos_in_pub_err.vv

@@ -0,0 +1,11 @@
+struct Log {}
+struct Xyz {}
+
+pub struct ThreadSafeLog {
+pub:
+    Log
+pub mut:
+    mu Xyz
+}
+
+fn main() {}