fix: allow creating directories in file sync local file picker (#199)

Closes #198.

I just assumed this was on by default 😭

In fact, the documentation says it is, but it's very clearly not!
```
/**
 `NSSavePanel`/`NSOpenPanel`: Set to `YES` to show the "New Folder" button. Default is `YES`.
 */
open var canCreateDirectories: Bool
```

Author: ethanndickson

Coder-Desktop/Coder-Desktop/Views/FileSync/FileSyncSessionModal.swift

@@ -28,6 +28,7 @@ struct FileSyncSessionModal<VPN: VPNService, FS: FileSyncDaemon>: View {
                         Button {
                             let panel = NSOpenPanel()
                             panel.directoryURL = FileManager.default.homeDirectoryForCurrentUser
+                            panel.canCreateDirectories = true
                             panel.allowsMultipleSelection = false
                             panel.canChooseDirectories = true
                             panel.canChooseFiles = false