feat: allow creating uninitialized context

[briaguya-ai]

example switch to allow cvar use before full init in SoH

Before

context = LUS::Context::CreateInstance("Ship of Harkinian", appShortName, "shipofharkinian.json", OTRFiles, {}, 3);

After

// init just what we need
context = LUS::Context::CreateUninitializedInstance("Ship of Harkinian", appShortName, "shipofharkinian.json");
context->InitLogging();
context->InitConfiguration();
context->InitConsoleVariables();

// prove we can get a value from a cvar now
int blarg = CVarGetInteger("gInterpolationFPS", 3);

// finish up the init
context->Init(OTRFiles, {}, 3);