[Wiki] Add Safe Space to the list

https://github.com/Kunzisoft/KeePassDX/wiki/File-Manager-and-Sync#file-manager-application

[Safe Space](https://f-droid.org/packages/org.privacymatters.safespace/) is similar to Anemo (works very well but the project looks _inactive_), please check it out and add to the table list. _Only supports Android 10 or newer_.

See their [FAQs](https://github.com/aashishksahu/SafeSpace#faq), especially "[Why should I use this app, XYZ app is better?](https://github.com/aashishksahu/SafeSpace/issues/8)"

Open the Wiki's File Manager and Sync page and inspect the file-manager application table. Review the linked Safe Space page and FAQs, then add Safe Space with its Android 10-or-newer requirement. Done means the table includes the app and accurately reflects the provided details.

Written by the indexing model from the issue text.