Fix override_text_color priority

[YgorSouza]

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 Text inside buttons ignores override_text_color in 0.32.0 #7367
• I have followed the instructions in the PR template

[YgorSouza]

For the record, here is where RichText does the same thing (and why it didn't have the same problem as noted in the issue):

egui/crates/egui/src/widget_text.rs

Lines 465 to 475 in 6fae65a

	fn get_text_color(&self, visuals: &Visuals) -> Option<Color32> {
	if let Some(text_color) = self.text_color {
	Some(text_color)
	} else if self.strong {
	Some(visuals.strong_text_color())
	} else if self.weak {
	Some(visuals.weak_text_color())
	} else {
	visuals.override_text_color
	}
	}

egui/crates/egui/src/widget_text.rs

Line 382 in 6fae65a

let text_color = self.get_text_color(&style.visuals);

egui/crates/egui/src/widget_text.rs

Line 404 in 6fae65a

let text_color = text_color.unwrap_or(crate::Color32::PLACEHOLDER);

[github-actions]

Preview available at https://egui-pr-preview.github.io/pr/7439-override-text-color-priority
Note that it might take a couple seconds for the update to show up after the preview_build workflow has completed.

[emilk]

Thanks! It would be great if you could add a simple snapshot test for this, e.g. in crates/egui_kittest/tests/regression_tests.rs

[emilk]

Nice - thank you! ❤️