Configure Nextcloud

- some keys in ~/.config/Nextcloud/nextcloud.cfg are set by
  the machine automatically when in use
- integrate Nextcloud in XDG user directories
- make Nextcloud run on login in Gnome
- add `run-private-scripts` utility to run shell scripts
  stored in the Nextcloud

.config/Nextcloud/nextcloud.cfg

@@ -0,0 +1,29 @@
+[General]
+confirmExternalStorage=false
+crashReporter=false
+monoIcons=true
+newBigFolderSizeLimit=999999
+optionalServerNotifications=false
+showCallNotifications=false
+useNewBigFolderSizeLimit=false
+
+[Accounts]
+0\Folders\1\ignoreHiddenFiles=false
+0\Folders\1\localPath=/home/alexander/data/
+0\Folders\1\paused=false
+0\Folders\1\targetPath=/
+0\Folders\1\version=2
+0\Folders\1\virtualFilesMode=off
+0\authType=webflow
+0\dav_user=alexander
+0\url=https://nextcloud.webartifex.biz
+0\user=@Invalid()
+0\version=1
+0\webflow_user=alexander
+version=2
+
+[Nextcloud]
+autoUpdateCheck=false
+
+[Proxy]
+type=2