Meta: Refactor the IPC-compiler and port it to LibMain

This does a few things in total:
* Ports the IPC-compiler to LibMain
* Extract some compiler steps into separate functions
* Minify some appends to use appendln (or appendff in the case of
  StringBuilder)

This reduces the clang-tidies maximum cognitive-complexity score for
this file from 325 to under 100.

Meta/Lagom/Tools/CodeGenerators/IPCCompiler/CMakeLists.txt

@@ -2,4 +2,4 @@ set(SOURCES
     main.cpp
 )
 
-lagom_tool(IPCCompiler)
+lagom_tool(IPCCompiler LIBS LagomMain)