syntax_tests: allow to update tests, and don't use a regexp (#8589)

* syntax_tests: allow to "bless" tests, and don't use a regexp

A regexp was used at the beginning because I thought we would want to
allow error to contains things that were not predictable or that would
often change. But this is not the case¹. It is better to actually test
for the full error message

¹ well actually it was the case for path, but there is another substitution to 
 `📂` for the manifest directory

* syntax_tests: Bless the tests

* syntax_tests: Manual adjust after bless

Because there used to be comments on the same line of the message which
bless don't support

* Fix error message with path on windows

 - The debug implementation of path make double slash, that's not what
   we want to show the user
 - normalize paths to use `/` so the test passes

internal/compiler/tests/syntax/functions/functions.slint

@@ -2,10 +2,12 @@
 // SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-2.0 OR LicenseRef-Slint-Software-3.0
 
 Abc := Rectangle {
+//  ^warning{':=' to declare a component is deprecated. The new syntax declare components with 'component MyComponent {'. Read the documentation for more info}
     function par() {}
 }
 
 export Xxx := Rectangle {
+//         ^warning{':=' to declare a component is deprecated. The new syntax declare components with 'component MyComponent {'. Read the documentation for more info}
     function fooo(a: int, a: int) -> int { return a; }
 //                        ^error{Duplicated argument name 'a'}
 

internal/compiler/tests/syntax/functions/functions_call.slint

@@ -12,6 +12,7 @@ global Glob {
 }
 
 Comp := Rectangle {
+//   ^warning{':=' to declare a component is deprecated. The new syntax declare components with 'component MyComponent {'. Read the documentation for more info}
     function f1() {}
     public function f2() {}
     protected function f3() {}
@@ -22,6 +23,7 @@ Comp := Rectangle {
 }
 
 export Xxx := Rectangle {
+//         ^warning{':=' to declare a component is deprecated. The new syntax declare components with 'component MyComponent {'. Read the documentation for more info}
     function foo(a: int) -> string { return a; }
 
     comp := Comp {}
@@ -37,7 +39,7 @@ export Xxx := Rectangle {
 //      ^error{The callback or function expects 1 arguments, but 0 are provided}
 
         root.foo.hello(45);
-        //       ^error{Cannot access fields of a function}
+//               ^error{Cannot access fields of a function}
 
         comp.f1();
 //           ^error{The function 'f1' is private. Annotate it with 'public' to make it accessible from other components}
@@ -54,7 +56,7 @@ export Xxx := Rectangle {
         45()()();
 //      ^error{The expression is not a function}
         (foo)(1);
-//       ^error{Function must be called. Did you forgot the '\(\)'}
+//       ^error{Function must be called. Did you forgot the '()'?}
 
     }
 

internal/compiler/tests/syntax/functions/functions_purity.slint

@@ -90,6 +90,7 @@ export component Bar {
 
 
 export Foo_Legacy := Rectangle {
+//                ^warning{':=' to declare a component is deprecated. The new syntax declare components with 'component MyComponent {'. Read the documentation for more info}
     property <int> prop;
     callback c1;
     pure callback c2;
@@ -149,6 +150,7 @@ export Foo_Legacy := Rectangle {
 
 
 export Bar_Legacy := Rectangle {
+//                ^warning{':=' to declare a component is deprecated. The new syntax declare components with 'component MyComponent {'. Read the documentation for more info}
     pure callback xc1 <=> f.c1;
 //  ^error{Purity of callbacks 'xc1' and 'f.c1' doesn't match}
     callback xc2 <=> f.c2;

internal/compiler/tests/syntax/functions/functions_purity_recursive_5220.slint

@@ -3,10 +3,10 @@
 
 export component App inherits Window{
     background: blue;
-    //          ^error{Function must be called}
+//              ^error{Function must be called. Did you forgot the '()'?}
     function blue()->color {
        blue
-//     ^error{Function must be called}
+//     ^error{Function must be called. Did you forgot the '()'?}
     }