Headless and GLFW Windows

[TomAtkinsonArm]

Description

Adds Headless and GLFW windows back to the project. Events are forwarded though the Event Bus interface.

No need to pass Platform anymore as the Event Bus acts as the communication mechanism.

Headless and GLFW tests included. GLFW tests will not work in the CI so these require VKB_TEST_GLFW locally. All GLFW tests pass locally. We could add a small compile time executable to automatically trigger GLFW tests if a GPU is available.