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/events/Windows.cpp

@@ -148,7 +148,7 @@ void Events::listener_mapWindow(void* owner, void* data) {
                     PWINDOW->m_iMonitorID = PMONITOR->ID;
                 } else {
                     if (isNumber(MONITORSTR)) {
-                        const long int MONITOR = std::stoi(MONITORSTR);
+                        const MONITORID MONITOR = std::stoi(MONITORSTR);
                         if (!g_pCompositor->getMonitorFromID(MONITOR))
                             PWINDOW->m_iMonitorID = 0;
                         else