Improve DB Installation Check (#1537)

[schast]

We have problems with the database check from time to time. Currently it is assumed that the database has already been initialized as soon as a config.php exists.

In most cases, the following error occurs:

PHP Fatal error:  Uncaught Error: Call to a member function fetchAll() on bool in /opt/app-root/src/adm_program/system/classes/Database.php:516
Stack trace:
#0 /opt/app-root/src/adm_program/system/classes/Database.php(442): Database->loadTableColumnsProperties()
#1 /opt/app-root/src/adm_program/system/classes/TableAccess.php(654): Database->getTableColumnsProperties()
#2 /opt/app-root/src/adm_program/system/classes/TableAccess.php(147): TableAccess->setColumnsInfos()
#3 /opt/app-root/src/adm_program/system/classes/TableAccess.php(109): TableAccess->clear()
#4 /opt/app-root/src/adm_program/system/classes/Session.php(62): TableAccess->__construct()
#5 /opt/app-root/src/adm_program/system/common.php(91): Session->__construct()
#6 /opt/app-root/src/adm_program/overview.php(18): require_once('...')
#7 {main}\n  thrown in /opt/app-root/src/adm_program/system/classes/Database.php on line 516
  127.0.0.1 "GET /adm_program/overview.php HTTP/1.1" 500 -

Therefore, the check should take place directly in the database and, if necessary, redirect to the installation page.

With the new check, the installation in the container can be significantly simplified, as most of the values are already available via the container configuration.

@Fasse: Can you please review the pull request (changes in adm_program) and test with a normal installation?

[schast]

current installation steps with Docker Container (6 steps with manually filled db options):

[schast]

new installation steps with Docker Container (3 steps with automatically filled by docker env variables).

With this changes the other steps are automatically skipped since all options are already set in config file.