Fix override_text_color priority (#7439)

The override_text_color is now used when rendering text from a String or
&str. This is consistent with the RichText variant and makes the option
behave as advertised, taking precedence over WidgetVisuals and
overriding the color for all text unless explicitly changed for a single
widget (via RichText or LayoutJob).

* Closes <https://github.com/emilk/egui/issues/7367>
* [x] I have followed the instructions in the PR template

---------

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

crates/egui/src/widget_text.rs

@@ -746,13 +746,17 @@ impl WidgetText {
     ) -> Arc<Galley> {
         match self {
             Self::Text(text) => {
+                let color = style
+                    .visuals
+                    .override_text_color
+                    .unwrap_or(crate::Color32::PLACEHOLDER);
                 let mut layout_job = LayoutJob::simple_format(
                     text,
                     TextFormat {
                         // We want the style overrides to take precedence over the fallback font
                         font_id: FontSelection::default()
                             .resolve_with_fallback(style, fallback_font),
-                        color: crate::Color32::PLACEHOLDER,
+                        color,
                         valign: default_valign,
                         ..Default::default()
                     },