Now that we have most of core free of shadowing, we can enable the
warning as an error to catch anything that may be remaining and also
eliminate this class of logic bug entirely.
Migrates a remaining common file over to the Common namespace, making it
consistent with the rest of common files.
This also allows for high-traffic FS related code to alias the
filesystem function namespace as
namespace FS = Common::FS;
for more concise typing.
Allows reporting more cases where logic errors may exist, such as
implicit fallthrough cases, etc.
We currently ignore unused parameters, since we currently have many
cases where this is intentional (virtual interfaces).
While we're at it, we can also tidy up any existing code that causes
warnings. This also uncovered a few bugs as well.
