Don't specialize Logging.handle_message

[whatsthecraic]

Similarly to the Julia implementation of Logging.handle_message(::ConsoleLogger, ...), the PR avoids specializing handle_message for the different combinations of arguments.

[kpamnany]

Attn: @vchuravy, @Keno, @KristofferC

[NHDaly]

LGTM, thank you. Especially since the inner call will simply be another dynamic dispatch, there's absolutely no reason to specialize this. 👍

EDIT: Oh, jk, i don't have merge rights on this repo I guess.

[KristofferC]

Looks uncontroversial so I'll merge.