internal: introduce new types to avoid unsigned int rollover and signed int overflow (#7216)

* framebuffer: avoid gluint overflow

GLuint was being initialized to -1 and rolling over to unsigned int max,
its defined behaviour but very unnecessery. add a bool and use it for
checking if allocated or not.

* opengl: avoid gluint rollover

-1 rolls over to unsigned int max, use 0xFF instead.

* core: big uint64_t to int type conversion

there were a few uint64_t to int implicit conversions overflowing int
and causing UB, make all monitor/workspaces/windows use the new
typedefs. also fix the various related 64 to 32 implicit conversions
going around found with -Wshorten-64-to-32

src/helpers/Timer.hpp

@@ -6,7 +6,7 @@ class CTimer {
   public:
     void                                         reset();
     float                                        getSeconds();
-    int                                          getMillis();
+    long                                         getMillis();
     const std::chrono::steady_clock::time_point& chrono() const;
 
   private: