allow int as a cellpath for select

[fdncred]

Description

This PR allows ints to be used as cell paths.

Before

❯ let index = 0
❯ locations | select $index
Error: nu::shell::cant_convert

  × Can't convert to cell path.
   ╭─[entry #26:1:1]
 1 │ locations | select $index
   ·                    ───┬──
   ·                       ╰── can't convert int to cell path
   ╰────

After

❯ let index = 0
❯ locations | select $index
╭#┬───────location────────┬city_column┬state_column┬country_column┬lat_column┬lon_column╮
│0│http://ip-api.com/json/│city       │region      │countryCode   │lat       │lon       │
╰─┴───────────────────────┴───────────┴────────────┴──────────────┴──────────┴──────────╯

User-Facing Changes

Tests + Formatting

After Submitting