Add a new set of logging macros based on fmtlib
Similar but not exactly the same as https://github.com/citra-emu/citra/pull/3533
Citra currently uses a different version of fmt, which does not support FMT_VARIADIC so
make_args is used instead. On the other hand, yuzu uses fmt 4.1.0 which doesn't have make_args yet
so FMT_VARIADIC is used.
Add a case of `Log::Level::Count` to all switch statements that
dispatch on `Log::Level`. The case simply asserts `false` and notes
the invalid log level.
It provided a large increase in complexity of the logging system while
having a negligible performance impact: the usage patterns of the ring
buffer meant that each log contended with the logging thread, causing
it to effectively act as a synchronous extra buffering.
Also removed some broken code related to filtering of subclasses which
was broken since it was introduced. (Which means no one ever used that
feature anyway, since, 8 months later, no one ever complained.)
