LibWasm: Add basic support for module instantiation and execution stubs

This adds very basic support for module instantiation/allocation, as
well as a stub for an interpreter (and executions APIs).
The 'wasm' utility is further expanded to instantiate, and attempt
executing the first non-imported function in the module.
Note that as the execution is a stub, the expected result is a zero.
Regardless, this will allow future commits to implement the JS
WebAssembly API. :^)

Userland/Libraries/LibWasm/CMakeLists.txt

@@ -1,4 +1,7 @@
 set(SOURCES
+    AbstractMachine/AbstractMachine.cpp
+    AbstractMachine/Configuration.cpp
+    AbstractMachine/Interpreter.cpp
     Parser/Parser.cpp
     Printer/Printer.cpp
 )