Fix settings import

[EricBAndrews]

Checklist

• I have read CONTRIBUTING.md
• I have described what this PR contains
• If this PR alters the UI, I have attached pictures/videos
• This PR addresses one or more open issues that were assigned to me:
  - closes Unable the Import Settings #1373

Pull Request Information

Fixes an issue where settings could not be imported unless created explicitly by Mlem

Repro (on-device)

• Export settings
• Duplicate the settings file
• Try to import the duplicated file
• Import fails: "the file couldn't be opened because you don't have permission"

Resolution
Properly request access as defined in the docs

[Sjmarf]

Looks good! Do we need to fileUrl.stopAccessingSecurityScopedResource() in the catch block? I'm not sure whether we're allowed to not call stopAccessingSecurityScopedResource and what the consequences of that would be

[EricBAndrews]

Nice catch--I've updated the logic to call it in the catch as well.

Per the docs:

If you fail to relinquish your access to file-system resources when you no longer need them, your app leaks kernel resources. If sufficient kernel resources leak, your app loses its ability to add file-system locations to its sandbox, such as with Powerbox or security-scoped bookmarks, until relaunched.

[Sjmarf]

Nice!