chore: import upstream snapshot with attribution

extra/proxy.ps1

@@ -0,0 +1,47 @@
+[CmdletBinding()]
+param(
+    [string]$version,
+    [string]$directory
+)
+
+$proxy = (Join-Path $directory 'lapce.exe')
+
+$LapceProcesses = (Get-Process -Name 'lapce' -EA SilentlyContinue).Count
+if ($LapceProcesses -ne 0) {
+    Write-Host 'Proxy currently in use. Aborting installation'
+    exit
+}
+
+if (Test-Path $proxy) {
+    Write-Host 'Proxy already installed'
+    exit
+}
+
+switch ($env:PROCESSOR_ARCHITECTURE) {
+    # Only x86_64 is supported currently
+    'AMD64' {
+        $arch = 'x86_64'
+    }
+}
+
+$url = "https://github.com/lapce/lapce/releases/download/${version}/lapce-proxy-windows-${arch}.gz"
+$gzip = Join-Path "${env:TMP}" "lapce-proxy-windows-${arch}.gz"
+
+$webclient = [System.Net.WebClient]::new()
+$webclient.DownloadFile($url, $gzip)
+$webclient.Dispose()
+
+[System.IO.Directory]::CreateDirectory($directory)
+
+$archive = [System.IO.File]::Open($gzip, [System.IO.FileMode]::Open)
+$proxy_file = [System.IO.File]::Create($proxy)
+$compressor = [System.IO.Compression.GZipStream]::new($archive, [System.IO.Compression.CompressionMode]::Decompress)
+$compressor.CopyTo($proxy_file)
+Start-Sleep -Seconds 3
+$compressor.close()
+$proxy_file.close()
+$archive.close()
+
+[System.IO.File]::Delete($gzip)
+
+Write-Host 'lapce-proxy installed'