UserspaceEmulator: Add a SoftMMU::read<T> function

...and implement SoftCPU::read_memory<T> with it.
This allows the MMU to read a typed object (using 1-byte reads), which
is significantly nicer to use than reading the struct fields manually.

Userland/DevTools/UserspaceEmulator/SoftMMU.cpp

@@ -376,4 +376,9 @@ bool SoftMMU::fast_fill_memory32(X86::LogicalAddress address, size_t count, Valu
     return true;
 }
 
+void SoftMMU::dump_backtrace()
+{
+    m_emulator.dump_backtrace();
+}
+
 }