Add the extension to KDE Falkon Extensions Store.

### Issue Details

Apparently KDE's designated web browser Falkon has [an extension store](https://store.kde.org/browse?cat=571), which has *very* few extensions available (19) and with no sideloading support, due to using a custom extension engine that does not seem to correspond to MV2, MV3, or XUL.

While this would make it somewhat hard to port and publish AdGuard Browser Extension there, it also means there seems to be a decent potential demographic for it, especially after I learned less than an hour ago that KDE Falkon builds for Windows have resumed after 8-ish years (https://github.com/microsoft/winget-pkgs/pull/375371).

### Proposed solution

Add AdGuard Browser Extension to KDE Store Falkon Extensions.

### Alternative solution

Somehow get KDE to dramatically revamp the Falkon source code to make it natively support MV2 extensions.