fix: unable to detect Color completion item hex code for some LSPs (#12501)

Co-authored-by: Nikita Revenco <154856872+NikitaRevenco@users.noreply.github.com>

helix-term/src/ui/completion.rs

@@ -92,8 +92,11 @@ impl menu::Item for CompletionItem {
                                 value, ..
                             }) => value,
                         };
-                        Color::from_hex(text)
+                        // Language servers which send Color completion items tend to include a 6
+                        // digit hex code at the end for the color. The extra 1 digit is for the '#'
+                        text.get(text.len().checked_sub(7)?..)
                     })
+                    .and_then(Color::from_hex)
                     .map_or("color".into(), |color| {
                         Spans::from(vec![
                             Span::raw("color "),