This PR splits the GUI source files from the core source files. The immediate goal is to allow the CLI to require only a minimum number of dynamic libraries. The long term goal is to create an architectural boundary around the core module, in preparation of libkdbx.
Fixes#5001.
The favicon download URL was constructed from scheme and host only. This is fixed by simply replacing the path of the original URL with "/favicon.ico", thus keeping scheme, host, auth and port intact.
Further modification: URL's with a non-http schema are now rejected.