### Godot version

v4.0.2.stable.official [7a0977ce2]

### System information

Windows 10, not platform specific

### Issue description

Methods `get_character_line` and `get_character_paragraph` return wrong indices for characters that are first in the respective line/paragraph. See the attached screenshot.

![image](https://user-images.githubusercontent.com/892180/236546781-692603be-eb09-419e-822e-d4152a66d9b6.png)


### Steps to reproduce

Run attached project.

The script goes through all characters in `RichTextLabel` and prints the respective character, line index, and paragraph index. None of them should be -1 since we are iterating through valid indices.

### Minimal reproduction project

[RichTextLabel.zip](https://github.com/godotengine/godot/files/11409399/RichTextLabel.zip)

continue;
						}
						int dif = table->columns[i].width - table->columns[i].max_width;
						if (dif > 0) {
							table_need_fit = true;
							table->columns[i].width = table->columns[i].max_width;
							table->total_width -= dif;
							total_ratio -= table->columns[i].expand_ratio;
						}
					}
					
					remaining_width = available_width - table->total_width;
					if (remaining_width > 0 && total_ratio > 0) {
						for (int i = 0; i < col_count; i++) {
							if (table->columns[i].expand) {
								int dif = table->columns[i].max_width - table->columns[i].width;
								if (dif > 0) {
									int slice = table->columns[i].expand_ratio * remaining_width / total_ratio;
									int incr = MIN(dif, slice);
									table->columns[i].width += incr;
									table->total_width += incr;
								}
							}
						}
					}
				}
				
				idx = 0;
				table->total_height = 0;
				table->rows.clear();