LibJS: Move Bytecode::Instruction::execute() to the Op.h header

..and make sure it always gets inlined in the interpreter loop.

Userland/Libraries/LibJS/Bytecode/Interpreter.cpp

@@ -8,6 +8,7 @@
 #include <LibJS/Bytecode/BasicBlock.h>
 #include <LibJS/Bytecode/Instruction.h>
 #include <LibJS/Bytecode/Interpreter.h>
+#include <LibJS/Bytecode/Op.h>
 #include <LibJS/Runtime/GlobalObject.h>
 
 namespace JS::Bytecode {