Fix ofx network

[oxillo]

As proposed in #6457

• Deprecate ofxNetworkCheckError()
• Add int ofxNetworkGetLastError() to return the last error
• Add void ofxNetworkLogError(int err, const char* file, int line) to log an error that happened on line line in file file
• Add ofxNetworkLogLastError() that is a shortcut for ofxNetworkLogError(ofxNetworkGetLastError(), FILE, LINE)

[ofTheo]

@oxillo thanks for this!!
To be totally honest, I am not sure I 100% understand the fix but the logic and approach seems sounds.

I'll give it a day to let @arturoc and maybe @bakercp to chime in.

But if there is no other feedback we can merge it tomorrow. It does pass the tests and I was seeing similar issues on macOS with errors in the TCP tests before which I don't see now.

Thanks again!