Kernel: Remove ContiguousVMObject, let AnonymousVMObject do the job

We don't need an entirely separate VMObject subclass to influence the
location of the physical pages.

Instead, we simply allocate enough physically contiguous memory first,
and then pass it to the AnonymousVMObject constructor that takes a span
of physical pages.

Kernel/VM/MemoryManager.cpp

@@ -17,7 +17,6 @@
 #include <Kernel/Sections.h>
 #include <Kernel/StdLib.h>
 #include <Kernel/VM/AnonymousVMObject.h>
-#include <Kernel/VM/ContiguousVMObject.h>
 #include <Kernel/VM/MemoryManager.h>
 #include <Kernel/VM/PageDirectory.h>
 #include <Kernel/VM/PhysicalRegion.h>
@@ -705,7 +704,7 @@ OwnPtr<Region> MemoryManager::allocate_contiguous_kernel_region(size_t size, Str
     auto range = kernel_page_directory().range_allocator().allocate_anywhere(size);
     if (!range.has_value())
         return {};
-    auto vmobject = ContiguousVMObject::try_create_with_size(size);
+    auto vmobject = AnonymousVMObject::try_create_physically_contiguous_with_size(size);
     if (!vmobject) {
         kernel_page_directory().range_allocator().deallocate(range.value());
         return {};