MAINTAINERS: Add entries for code tagging and memory allocation profiling

The new code & libraries added are being maintained - mark them as such.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>