LibJS/Bytecode: Add Call opcode for fixed-argument-count calls

This avoids the overhead of allocating a new Array on every function
call, saving a substantial amount of time and avoiding GC thrash.

This patch only makes use of Op::Call in CallExpression. There are other
places we should codegen this op. We should also do the same for super
expression calls.

~5% speed-up on Kraken/stanford-crypto-ccm.js

Userland/Libraries/LibJS/Bytecode/Pass/LoadElimination.cpp

@@ -124,6 +124,7 @@ static NonnullOwnPtr<BasicBlock> eliminate_loads(BasicBlock const& block, size_t
             // Attribute accesses (`a.o` or `a[o]`) may result in calls to getters or setters
             // or may trigger proxies
             // So these are treated like calls
+        case Call:
         case CallWithArgumentArray:
             // Calls, especially to local functions and eval, may poison visible and
             // cached variables, hence we need to clear the lookup cache after emitting them