use 0-indexing in explore (#15079)

# Description
The index in `explore --index` starting with 1 is inconsistent with rest
of nushell. Also it tripped me up a few times when I wanted to select a
row with `:nu get n`

# User-Facing Changes
Index in `explore --index` now starts with 0.

# Tests + Formatting

- 🟢 toolkit fmt
- 🟢 toolkit clippy
- 🟢 toolkit test
- 🟢 toolkit test stdlib

# After Submitting
N/A

crates/nu-explore/src/views/record/table_widget.rs

@@ -502,7 +502,7 @@ impl<'a> IndexColumn<'a> {
 impl Widget for IndexColumn<'_> {
     fn render(self, area: Rect, buf: &mut Buffer) {
         for row in 0..area.height {
-            let i = 1 + row as usize + self.start;
+            let i = row as usize + self.start;
             let text = i.to_string();
             let style = nu_style_to_tui(self.style_computer.compute(
                 "row_index",