Shorthands for bottom accents

[Enivex]

A recent issue in the typst repository (typst/typst#5846) made me realize that we're missing shorthands for a ton of bottom accents (and some regular accents too). Here's a selection (not exhaustive)

#show math.equation: set text(font: "STIX Two Math")

Bottom version of `macron` (not stretchable)
$
  accent(x, \u{331}) 
$

Bottom version of `dash`
$
  accent(x y,\u{332})
$

Bottom version of `tilde`
$
  accent(x y,\u{330})
$

Bottom versions of arrows
$
  accent(x y,\u{20ee}) quad accent(x y,\u{20ef}) quad accent(x  y,\u{34d})
$

Bottom versions of harpoons
$
  accent(x y,\u{20ec}) quad accent(x y,\u{20ed}) 
$

Bottom dots
$
  accent(x,\u{323}) quad accent(x,\u{324}) quad accent(x,\u{20e8})
$