[Suggestion] Allow user to disable index in inline-history

[elseawhy]

Right now an index is showed when inline-history is enabled, there is no way to disable this and the only way to remove this now is by commenting out line 851 to 861 in src/app/ui.rs

line 851 - 861:

                        let mut extra_info_text = format!(" #idx={}", sug.index);
                        if let Some(ts) = sug.timestamp {
                            let time_ago_str = ts.format_timeago_5chars();
                            extra_info_text.push_str(&format!(" {}", time_ago_str.trim_start()));
                        }

                        content.write_tagged_span_dont_overwrite(&TaggedSpan::new(
                            Span::from(extra_info_text)
                                .style(crate::settings().colour_palette.inline_suggestion()),
                            Tag::HistorySuggestion,
                        ));

Suggestion: Allow user to enable/disable it.