fix: Trust the filesystem to move files

The original lib/util/move-file.js has gone through many iterations over
the last several years.  It no longer represents anything close to the
original intent.

Most of the functionality it was originally trying to work around is now
something that `@npmcli/fs#moveFile` does, and better.  Trying to move a
file by creating a hard link and unlinking the old file is an
optimization best left to the operating system when you ask it to move a
file.  In fact the `@npmcli/fs#moveFile` method tries a *rename* first,
which is the best choice all around.  It also supports an "overwrite:
false" flag so we can still error out if the destination already exists.

This PR removes all of the old legacy code.

lib/content/write.js

@@ -4,7 +4,7 @@ const events = require('events')
 
 const contentPath = require('./path')
 const fs = require('fs/promises')
-const moveFile = require('../util/move-file')
+const { moveFile } = require('@npmcli/fs')
 const { Minipass } = require('minipass')
 const Pipeline = require('minipass-pipeline')
 const Flush = require('minipass-flush')
@@ -161,8 +161,14 @@ async function moveToDestination (tmp, cache, sri, opts) {
   const destDir = path.dirname(destination)
 
   await fs.mkdir(destDir, { recursive: true })
-  await moveFile(tmp.target, destination)
-  tmp.moved = true
+  try {
+    await moveFile(tmp.target, destination, { overwrite: false })
+    tmp.moved = true
+  } catch (err) {
+    if (!err.message.startsWith('The destination file exists')) {
+      throw Object.assign(err, { code: 'EEXIST' })
+    }
+  }
 }
 
 function sizeError (expected, found) {

test/content/write.js

@@ -233,6 +233,22 @@ t.test('cleans up tmp on successful completion', async t => {
   })
 })
 
+t.test('Handles moveFile error other than EEXIST', async t => {
+  const write = t.mock('../../lib/content/write.js', {
+    '@npmcli/fs': {
+      moveFile: async () => {
+        throw new Error('Unknown error')
+      },
+    },
+  })
+  const CONTENT = 'foobarbaz'
+  const CACHE = t.testdir()
+  await t.rejects(
+    write.stream(CACHE).end(CONTENT).promise(),
+    { message: 'Unknown error' }
+  )
+})
+
 t.test('cleans up tmp on streaming error', (t) => {
   const CONTENT = 'foobarbaz'
   const CACHE = t.testdir()