Improve PHP 8.1 support for Installer

[carryel]

Describe the bug

In php8, a number of notices have been converted into warnings(https://www.php.net/manual/en/migration80.incompatible.php):

• Attempting to read an undefined array key.

When I tried to install cacti(both cacti-1.2.26 and develop) in php8, I met the following errors.

...
Warning: Undefined array key "name" in /usr/local/src/cacti-develop/lib/installer.php on line 1301

Warning: Undefined array key "name" in /usr/local/src/cacti-develop/lib/installer.php on line 1302

Warning: Undefined array key "name" in /usr/local/src/cacti-develop/lib/installer.php on line 1303

Warning: Undefined array key "name" in /usr/local/src/cacti-develop/lib/installer.php on line 1311

Warning: Undefined array key "name" in /usr/local/src/cacti-develop/lib/installer.php on line 1301

Warning: Undefined array key "name" in /usr/local/src/cacti-develop/lib/installer.php on line 1302
...

When I debugged this, I found that it appears when some PHP modules are not installed such as simplexml and zlib.

https://github.com/Cacti/cacti/blob/develop/install/functions.php#L620 https://github.com/Cacti/cacti/blob/develop/lib/installer.php#L1301

Here are the contents of the array in issue(in my debugging logs).

...
2024-02-06 14:41:55 - INSTALL-TEMPLATES: always: known array: Array ( [filename] => ACME.xml.gz )
405 2024-02-06 14:41:55 - INSTALL-TEMPLATES: always: known array: Array ( [filename] => ACME.xml.gz [name] =>     ACME.xml.gz )
406 2024-02-06 14:41:55 - INSTALL-TEMPLATES: always: known array: Array ( [filename] => AKCP_Device.xml.gz )
407 2024-02-06 14:41:55 - INSTALL-TEMPLATES: always: known array: Array ( [filename] => AKCP_Device.xml.gz [na    me] => AKCP_Device.xml.gz )
408 2024-02-06 14:41:55 - INSTALL-TEMPLATES: always: known array: Array ( [filename] => APC_InfraStruXure_InRo    w_CRAC.xml.gz )
409 2024-02-06 14:41:55 - INSTALL-TEMPLATES: always: known array: Array ( [filename] => APC_InfraStruXure_InRo    w_CRAC.xml.gz [name] => APC_InfraStruXure_InRow_CRAC.xml.gz )
...

The arrays are overlapping, and one of the overlapping arrays does not have a name key.

From the php8 version below, instructions for not installing are clearly displayed during the installation process.

To Reproduce

Steps to reproduce the behavior:

Install PHP8 excluding PHP's zlib module. And install any cacti versions.

Expected behavior

Instructions for not installing should be displayed during the installation process.

Screenshots

Additional context

Add any other context about the problem here.