Modernization + AZStd::function compare fix. (#3680)

* Modernization + small fix.

Modernize ( `bool`/`override`/other) code in AzCore, AzFramework, AzQtComponents, AzToolsFramework, etc.
Replaced a `bind` or two, use `using` in a few places as well.

Fix nullptr comparison of AZStd::function.

Signed-off-by: nemerle <96597+nemerle@users.noreply.github.com>

* Apply review-based changes

Signed-off-by: nemerle <96597+nemerle@users.noreply.github.com>

Code/Framework/AzFramework/Platform/Linux/AzFramework/Application/Application_Linux.cpp

@@ -24,7 +24,7 @@ namespace AzFramework
             LinuxXcbConnectionManagerBus::Handler::BusConnect();
         }
 
-        ~LinuxXcbConnectionManagerImpl()
+        ~LinuxXcbConnectionManagerImpl() override
         {
             LinuxXcbConnectionManagerBus::Handler::BusDisconnect();
             xcb_disconnect(m_xcbConnection);   

Code/Framework/AzFramework/Platform/Linux/AzFramework/Process/ProcessCommunicator_Linux.cpp

@@ -78,7 +78,7 @@ namespace AzFramework
             FD_ZERO(&set);
             FD_SET(handle->GetHandle(), &set);
 
-            [[maybe_unused]] int numReady = select(handle->GetHandle() + 1, &set, NULL, NULL, NULL);
+            [[maybe_unused]] int numReady = select(handle->GetHandle() + 1, &set, nullptr, nullptr, nullptr);
 
             // if numReady == -1 and errno == EINTR then the child process died unexpectedly and
             // the handle was closed. Not something to assert about in regards to trying to read

Code/Framework/AzFramework/Platform/Linux/AzFramework/Process/ProcessWatcher_Linux.cpp

@@ -277,7 +277,7 @@ namespace AzFramework
                 environmentVariables[i][0] = '\0';
                 azstrcat(environmentVariables[i], envVarString.size(), envVarString.c_str());
             }
-            environmentVariables[numEnvironmentVars] = NULL;
+            environmentVariables[numEnvironmentVars] = nullptr;
         }
 
         pid_t child_pid = fork();
@@ -373,7 +373,7 @@ namespace AzFramework
         }
 
         bool isProcessDone = false;
-        time_t startTime = time(0);
+        time_t startTime = time(nullptr);
         time_t currentTime = startTime;
         AZ_Assert(currentTime != -1, "time(0) returned an invalid time");
         while (((currentTime - startTime) < waitTimeInSeconds) && !isProcessDone)
@@ -385,7 +385,7 @@ namespace AzFramework
                 m_pWatcherData->m_childProcessIsDone = true;
                 break;
             }
-            currentTime = time(0);
+            currentTime = time(nullptr);
         }
         //returns false if process is still running after time
         return isProcessDone;