feat: use `ibis.desc()`/`.desc()` with selectors about ibis HOT 3 CLOSED

In [8]: from ibis.interactive import *

In [9]: t = ex.penguins.fetch()

In [10]: expr = t.select("species", "island").value_counts().order_by(s.across(s.contains("count"), _.desc()))

In [11]: ibis.to_sql(expr)
Out[11]:
SELECT
  *
FROM (
  SELECT
    "t1"."species",
    "t1"."island",
    COUNT(*) AS "species_island_count"
  FROM (
    SELECT
      "t0"."species",
      "t0"."island"
    FROM "penguins" AS "t0"
  ) AS "t1"
  GROUP BY
    1,
    2
) AS "t2"
ORDER BY
  "t2"."species_island_count" DESC

In [12]: expr
Out[12]:
┏━━━━━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━┓
┃ species   ┃ island    ┃ species_island_count ┃
┡━━━━━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━┩
│ string    │ string    │ int64                │
├───────────┼───────────┼──────────────────────┤
│ Gentoo    │ Biscoe    │                  124 │
│ Chinstrap │ Dream     │                   68 │
│ Adelie    │ Dream     │                   56 │
│ Adelie    │ Torgersen │                   52 │
│ Adelie    │ Biscoe    │                   44 │
└───────────┴───────────┴──────────────────────┘