LibSQL: Add missing header includes

These are explicitly needed, and will cause compile errors as headers
moved around in subsequent commits.

Userland/Libraries/LibSQL/Database.h

@@ -13,6 +13,7 @@
 #include <LibSQL/Forward.h>
 #include <LibSQL/Heap.h>
 #include <LibSQL/Meta.h>
+#include <LibSQL/Serializer.h>
 
 namespace SQL {
 

Userland/Libraries/LibSQL/Index.cpp

@@ -7,6 +7,7 @@
 #include <LibSQL/Heap.h>
 #include <LibSQL/Index.h>
 #include <LibSQL/Meta.h>
+#include <LibSQL/TupleDescriptor.h>
 
 namespace SQL {
 

Userland/Libraries/LibSQL/Index.h

@@ -9,6 +9,7 @@
 #include <LibCore/Object.h>
 #include <LibSQL/Forward.h>
 #include <LibSQL/Meta.h>
+#include <LibSQL/Serializer.h>
 
 namespace SQL {