[rcore] Support window flags with initialization issues
This may not be the correct approach, however this appears to work. The idea is that before modifying `CORE.Window.flags` when first creating the window we keep a copy of the flags in order to call `SetWindowState` after initialization has completed, which should behave as if `MaximizeWindow` or `MinimizeWindow`, or conceptually any other flag modifying function were called after `InitWindow`.
This pull request only performs this for the windows platform, modify as needed in the switch statement at the end for others.