Add some system actions

[EugeneOne1]

Originally proposed by @uservictor in #2462 (comment):

Maybe it would be helpful to add an seperate menu for "system" settings.
Between General settings and DNS settings you can add System settings.

It can contain options like:
Reinstall
Choose Update channel (edge) (beta) (stable)
Choose System language

Service restart
Disable protection
Report Issue

[Aikatsui]

Maybe it would be helpful to add an seperate menu for "system" settings.
Between General settings and DNS settings you can add System settings.

#1685

Reinstall, Service restart #2048
Choose Update channel (edge) (beta) (stable) #2420
Choose System language #997
Disable protection - It is available or #1558
Report Issue #1133

[DandelionSprout]

• Disable protection: Add @@*$important whenever needed, I at least presume.
• Choose system language: Available in the bottom right of most control panel pages.
• Report issue: Available in the bottom left of most control panel pages.

[gyCfjSnO]

Problem Description
Can't restart AdGuard from Web GUI

Proposed Solution
Have a restart service/reboot device button on the Web GUI

[uservictor]

Please add:

• Clear` "DNS cache" entrys button
• Disable/Enable DNS cache button

And if possible show short path if custom filter.txt is added to AGH default folder.

This is how it looks now:
home/pi/AdGuardHome/data/filters/list.txt
Maybe you can show like this:
filters/list.txt or
~/filters/list.txt