Converts many of the Find* functions to return a std::optional<T> as
opposed to returning the raw return values directly. This allows
removing a few assertions and handles error cases like the service
itself does.

This member function doesn't actually modify instance state, so it can
be marked as a const member function.

This was missed within #2075. Renames the member function to make it
consistent with the rest of the Find* functions.

Co-Authored-By: FernandoS27 <fsahmkow27@gmail.com>

Also remove "enabled" field from Tegra::Texture::FullTextureInfo because
it would become unused.

A holdover from citra, the Horizon kernel on the switch has no
prominent kernel object that functions as a timer. At least not
to the degree of sophistication that this class provided.

As such, this can be removed entirely. This class also wasn't used at
all in any meaningful way within the core, so this was just code sitting
around doing nothing. This also allows removing a few things from the
main KernelCore class that allows it to use slightly less resources
overall (though very minor and not anything really noticeable).

Co-Authored-By: ReinUsesLisp <reinuseslisp@airmail.cc>