feature: Added web validation (#7474)

* refactor: convert validations to modules to prep for gui integration

* accidentally dropped, schema update

* fix accidental output to webui

* mention discovery-wrapper.py and re-arrange.

* refine some fix statements

* rename the Config validation group to Configuration.

* fix some scrutinizer issues
remove as many local functions from validator.php as possible
move extensions from pre-check
remove duplicate timezone check
looks like there is some db schema differences between mariadb 10.1 and 10.2, investigating

* mariadb version diff take2

* Check schema version first for database.
Remove stop to go back to command line for install docs.
Add helpful link when there is no devices added to /addhost

* fix incorrect validation for empty string defaults

* Fix style

* Add additional file permissions checks

* catch exception and fail for invalid timezone
Change visuals a bit.

* add php version warning

* fix space

discovery.php

@@ -63,7 +63,7 @@ if (isset($options['i']) && $options['i'] && isset($options['n'])) {
 }
 
 if (isset($options['d']) || isset($options['v'])) {
-    $versions = version_info(false);
+    $versions = version_info();
     echo <<<EOH
 ===================================
 Version info: