Kernel: Add typed_map<T>(PhysicalAddress) and use it in ACPI parsing

There was a frequently occurring pattern of "map this physical address
into kernel VM, then read from it, then unmap it again".

This new typed_map() encapsulates that logic by giving you back a
typed pointer to the kind of structure you're interested in accessing.

It returns a TypedMapping<T> that can be used mostly like a pointer.
When destroyed, the TypedMapping object will unmap the memory. :^)

Kernel/Interrupts/InterruptManagement.cpp

@@ -127,7 +127,7 @@ RefPtr<IRQController> InterruptManagement::get_responsible_irq_controller(u8 int
 PhysicalAddress InterruptManagement::search_for_madt()
 {
     dbg() << "Early access to ACPI tables for interrupt setup";
-    auto rsdp = ACPI::StaticParsing::search_rsdp();
+    auto rsdp = ACPI::StaticParsing::find_rsdp();
     if (rsdp.is_null())
         return {};
     return ACPI::StaticParsing::search_table(rsdp, "APIC");