Improve indication of API server address

[dforsi]

The API server is accepting commands on port 8091 of all interfaces but the about dialog shows only 127.0.0.1:8091 and it is labeled as the address of the documentation:

and the log messages print an empty string as address:

2024-07-20 20:57:50.191 (I) WebAPIServer::start: starting web API server at http://:8091
2024-07-20 20:59:07.028 (I) WebAPIServer::stop: stopped web API server at http://:8091

This PR tries to improve the information about the IP address in tha About dialog changing the label and using the address 0.0.0.0 as used in in httplistener.cpp and according to the documentation at https://doc.qt.io/qt-6/qhostaddress.html#toString which says that QHostAddress::Any is indicated with the address 0.0.0.0 even if it is listening on both IPv4 and IPv6.

2024-07-20 22:13:34.488 (I) WebAPIServer::start: starting web API server at http://0.0.0.0:8091
2024-07-20 22:14:06.499 (I) WebAPIServer::stop: stopped web API server at http://0.0.0.0:8091

The problem is that using 0.0.0.0 and [::] in Firefox and Chrome work in Linux but not in Windows.
On Linux all the following addresses open the pages of the API server:

1. http://127.0.0.1:8091/

2. http://[::1]:8091/

3. http://0.0.0.0:8091/

4. http://[::]:8091/

plus any other address assigned to wired, wireless or virtual interfaces.
On Windows # 3 and # 4 give ERR_ADDRESS_INVALID.

An alternative would be print 0.0.0.0 in the log and 127.0.0.0 in the About dialog but adding something like "and other interfaces", maybe only on Windows.