[Feature Request] Extract icon from installed apps.

[su226]

Is your feature request related to a problem? Please describe.
Currently icons could only be added manually via file, which is not convinent. And some website's favicon (downloaded manually or with KeePassXC) is not clear enough for a HiDPI screen like phone.

Describe the solution you'd like
Add a app selector to extract icons from installed apps. For apps with 2-layer icon, add a option to merge background and foreground, or use foreground only.
Also, if an entry's url scheme is androidapp://, or contains field like AndroidApp*, put the app(s) at the top to suggest it, if it's installed.

Describe alternatives you've considered

1. Download icons from website's favicon, apple-touch-icon or manifest.json: Feature: Auto-download and assign website's icons #596 (The latter two are better, because these icons usually have higher resolution.)
2. In-app simpleicons.org downloader, with a option not to colorize the icon or colorize with a custom color (instead of the brand color).
3. Make the "app icon extractor" in a seperate app like Add a custom content provider that can download icons #1449 (maybe put all three functions in one same app)

Additional context
N/A

[serrq]

I don't want this feature by default. Images can hiding dangerous code behind an innocent .png or .jpeg file.

That's because I switched to safest monochrome icons. And they already are located within the app.