filter_input -> filter_var

[DamImpr]

I reinstated the filter_input methods and added filter_var.
In FastCGI/FPM environments, filter_input is unreliable. Data is read directly from the raw input buffer managed by SAPI. This means that in containerised environments, data reading between the web server and fpm may fail. Alternatively, in some bad practices, where information is overwritten, unexpected results may occur.

[snipershady]

https://top10proactive.owasp.org/the-top-10/c3-validate-input-and-handle-exceptions/#allowlisting-vs-denylisting

`"Never trust provided data! Screen all data for malicious patterns or, even better, check all data against an allow list."

"Always perform Input validation on the server side for security. While client-side validation is useful for both functional and security purposes, it is easily bypassed."`

[DamImpr]

...i don't think I mentioned client-side validation anywhere in my PR 😅....

[DamImpr]

Thanks Nicolas