Add a theme constant to change LineEdit and TextEdit's caret width

This can be useful to improve caret visibility, especially at
larger font sizes. This can also be used for accessibility purposes.

doc/classes/LineEdit.xml

@@ -383,7 +383,7 @@
 	</constants>
 	<theme_items>
 		<theme_item name="caret_color" data_type="color" type="Color" default="Color(0.94, 0.94, 0.94, 1)">
-			Color of the [LineEdit]'s caret (text cursor).
+			Color of the [LineEdit]'s caret (text cursor). This can be set to a fully transparent color to hide the caret entirely.
 		</theme_item>
 		<theme_item name="clear_button_color" data_type="color" type="Color" default="Color(0.88, 0.88, 0.88, 1)">
 			Color used as default tint for the clear button.
@@ -406,6 +406,9 @@
 		<theme_item name="selection_color" data_type="color" type="Color" default="Color(0.49, 0.49, 0.49, 1)">
 			Color of the selection rectangle.
 		</theme_item>
+		<theme_item name="caret_width" data_type="constant" type="int" default="1">
+			The caret's width in pixels. Greater values can be used to improve accessibility by ensuring the caret is easily visible, or to ensure consistency with a large font size.
+		</theme_item>
 		<theme_item name="minimum_character_width" data_type="constant" type="int" default="4">
 			Minimum horizontal space for the text (not counting the clear button and content margins). This value is measured in count of 'M' characters (i.e. this amount of 'M' characters can be displayed without scrolling).
 		</theme_item>

doc/classes/TextEdit.xml

@@ -1223,7 +1223,7 @@
 			[Color] of the text behind the caret when using a block caret.
 		</theme_item>
 		<theme_item name="caret_color" data_type="color" type="Color" default="Color(0.88, 0.88, 0.88, 1)">
-			[Color] of the caret.
+			[Color] of the caret. This can be set to a fully transparent color to hide the caret entirely.
 		</theme_item>
 		<theme_item name="current_line_color" data_type="color" type="Color" default="Color(0.25, 0.25, 0.26, 0.8)">
 			Background [Color] of the line containing the caret.
@@ -1252,6 +1252,9 @@
 		<theme_item name="word_highlighted_color" data_type="color" type="Color" default="Color(0.8, 0.9, 0.9, 0.15)">
 			Sets the highlight [Color] of multiple occurrences. [member highlight_all_occurrences] has to be enabled.
 		</theme_item>
+		<theme_item name="caret_width" data_type="constant" type="int" default="1">
+			The caret's width in pixels. Greater values can be used to improve accessibility by ensuring the caret is easily visible, or to ensure consistency with a large font size. If set to [code]0[/code] or lower, the caret width is automatically set to 1 pixel and multiplied by the display scaling factor.
+		</theme_item>
 		<theme_item name="line_spacing" data_type="constant" type="int" default="4">
 			Sets the spacing between the lines.
 		</theme_item>

scene/gui/line_edit.cpp

@@ -780,8 +780,6 @@ void LineEdit::_notification(int p_what) {
 				ofs_max -= r_icon->get_width();
 			}
 
-			int caret_width = Math::round(1 * get_theme_default_base_scale());
-
 			// Draw selections rects.
 			Vector2 ofs = Point2(x_ofs + scroll_offset, y_ofs);
 			if (selection.enabled) {
@@ -843,6 +841,8 @@ void LineEdit::_notification(int p_what) {
 			// Draw carets.
 			ofs.x = x_ofs + scroll_offset;
 			if (draw_caret || drag_caret_force_displayed) {
+				const int caret_width = get_theme_constant(SNAME("caret_width")) * get_theme_default_base_scale();
+
 				if (ime_text.length() == 0) {
 					// Normal caret.
 					CaretInfo caret = TS->shaped_text_get_carets(text_rid, caret_column);

scene/gui/text_edit.cpp

@@ -1244,7 +1244,7 @@ void TextEdit::_notification(int p_what) {
 					}
 
 					// Carets.
-					int caret_width = Math::round(1 * get_theme_default_base_scale());
+					const int caret_width = get_theme_constant(SNAME("caret_width")) * get_theme_default_base_scale();
 
 					if (!clipped && caret.line == line && line_wrap_index == caret_wrap_index) {
 						caret.draw_pos.y = ofs_y + ldata->get_line_descent(line_wrap_index);

scene/resources/default_theme/default_theme.cpp

@@ -407,6 +407,7 @@ void fill_default_theme(Ref<Theme> &theme, const Ref<Font> &default_font, const
 
 	theme->set_constant("minimum_character_width", "LineEdit", 4);
 	theme->set_constant("outline_size", "LineEdit", 0);
+	theme->set_constant("caret_width", "LineEdit", 1);
 
 	theme->set_icon("clear", "LineEdit", make_icon(line_edit_clear_png));
 
@@ -451,6 +452,7 @@ void fill_default_theme(Ref<Theme> &theme, const Ref<Font> &default_font, const
 
 	theme->set_constant("line_spacing", "TextEdit", 4 * scale);
 	theme->set_constant("outline_size", "TextEdit", 0);
+	theme->set_constant("caret_width", "TextEdit", 1);
 
 	// CodeEdit