Report usage of deprecated functions - zeek::confirm_protocol()

[awelzel]

The zeek::confirm_protocol() method is documented as "deprecated". Compiling a .spicy file with a hook that calls zeek::confirm_protocol() does not trigger a deprecation warning or some form of notification to the user that spicy::accept_input() should be used.

I haven't looked in detail, maybe I'm not using the right flags, but think warning should be produced by default.

[bbannier]

This function and zeek::reject_protocol is part of the spicy-plugin functionality in Zeek, https://github.com/zeek/zeek/blob/7e11501d3cdee54482fcce9c9a640cabfe13d2c2/scripts/spicy/zeek.spicy#L9-L20. To trigger a deprecation warning for it we probably would need to add support for a &deprecated attribute to Spicy, decorate these functions, and trigger a message for use of such functions.