general: Remove unused boost inclusions where applicable

Cleans up unused includes and trims off some dependencies on externals.

src/core/file_sys/fsmitm_romfsbuild.h

@@ -27,7 +27,6 @@
 #include <map>
 #include <memory>
 #include <string>
-#include <boost/detail/container_fwd.hpp>
 #include "common/common_types.h"
 #include "core/file_sys/vfs.h"
 

src/core/hle/kernel/mutex.cpp

@@ -6,8 +6,6 @@
 #include <utility>
 #include <vector>
 
-#include <boost/range/algorithm_ext/erase.hpp>
-
 #include "common/assert.h"
 #include "core/core.h"
 #include "core/hle/kernel/errors.h"

src/yuzu/debugger/wait_tree.h

@@ -11,7 +11,6 @@
 #include <QAbstractItemModel>
 #include <QDockWidget>
 #include <QTreeView>
-#include <boost/container/flat_set.hpp>
 #include "common/common_types.h"
 #include "core/hle/kernel/object.h"