refactor: use zx

zx is a much simpler way to run commands.
It's a much higher level library than child_process,
so the code is much simpler to read.
Length-wise, it's about the same, but slightly longer,
primarily because Prettier wraps lists but not strings.
I also converted the remaining bits of sync io to async io,
as async io is only faster the more you use it.
It also encourages function coloring,
which makes it more explicit where there's io.
(Yes, I know function coloring is generally a bad thing.)

package.json

@@ -110,7 +110,8 @@
     "ls-engines": "^0.9.3",
     "prettier": "^2.8.8",
     "turbo": "^2.2.3",
-    "typescript": "~5.6.3"
+    "typescript": "~5.6.3",
+    "zx": "^8.2.4"
   },
   "packageManager": "[email protected]+sha512.dc700d97c8bd0ca9d403cf4fe0a12054d376f048d27830a6bc4a9bcce02ec42143cdd059ce3525f7dce09c6a4e52e9af5b996f268d8729c8ebb1cfad7f2bf51f",
   "engines": {

test/run-snapshots/new-package.txt

@@ -1,3 +1,25 @@
+- Adding elm.json
+✔ Adding elm.json
+- Adding package.json
+✔ Adding package.json
+- Adding elm-tooling.json
+✔ Adding elm-tooling.json
+- Adding README
+✔ Adding README
+- Adding preview folder
+✔ Adding preview folder
+- Adding rule - No.Doing.Foo
+✔ Adding rule - No.Doing.Foo
+- Adding .gitignore
+✔ Adding .gitignore
+- Adding GitHub Actions
+✔ Adding GitHub Actions
+- Adding LICENSE npx license BSD-3-Clause
+✔ Adding LICENSE npx license BSD-3-Clause
+- Adding elm-review configuration
+✔ Adding elm-review configuration
+- Adding maintenance scripts
+✔ Adding maintenance scripts
 
 All done! ✔