Minor ECS upgrade

[anticitizn]

• Make Input Manager global & extern it on headers that need it
• Add static constructors to components and systems to set their own Signature and self-register with the Coordinator & Input Manager
• Make game context a global as well, no point in having it static if other more important stuff is global anyway..

[anticitizn]

Making components self-registering while retaining aggregate initialization as it is now is a big pain in the ass, not worth

[anticitizn]

Put some asserts in Coordinator to check if a component was added before using it, right now it segfaults, which is the real issue