LibWasm: Start implementing a basic WebAssembly binary format parser

This can currently parse a really simple module.
Note that it cannot parse the DataCount section, and it's still missing
almost all of the instructions.
This commit also adds a 'wasm' test utility that tries to parse a given
webassembly binary file.
It currently does nothing but exit when the parse fails, but it's a
start :^)

Userland/Libraries/LibWasm/CMakeLists.txt

@@ -0,0 +1,6 @@
+set(SOURCES
+    Parser/Parser.cpp
+)
+
+serenity_lib(LibWasm wasm)
+target_link_libraries(LibWasm LibC LibCore)