More robust application of access permissions (#5062)

* More robust application of access permissions
We were in particular missing directory traversal `+X` in our current recommendations.
Extracted to own shell script so it can easily be invoked.
Update access permissions in Docker to account to be more robust.
#fix https://github.com/FreshRSS/FreshRSS/discussions/5037

* Minor simplification

* Restrict mkdir permissions
Default mkdir permissions are 0777, which is not good for security, so downgrade to 0770.

cli/_cli.php

@@ -44,7 +44,7 @@ function cliInitUser($username) {
 
 function accessRights() {
 	echo 'ℹ️ Remember to re-apply the appropriate access rights, such as:',
-		"\t", 'sudo chown -R :www-data . && sudo chmod -R g+r . && sudo chmod -R g+w ./data/', "\n";
+		"\t", 'sudo cli/access-permissions.sh', "\n";
 }
 
 function done($ok = true) {