Add an advanced preference to make the session restored banner optional. Issue 4988.

sources/VT100Screen.m

@@ -4552,7 +4552,7 @@ static void SwapInt(int *a, int *b) {
     }
     LineBuffer *lineBuffer = [[LineBuffer alloc] initWithDictionary:dictionary];
-    if (includeRestorationBanner) {
+    if (includeRestorationBanner && [iTermAdvancedSettingsModel showSessionRestoredBanner]) {
         [lineBuffer appendMessage:@"Session Restored"];
     }
     [lineBuffer setMaxLines:maxScrollbackLines_];

sources/iTermAdvancedSettingsModel.h

@@ -140,6 +140,7 @@
 + (BOOL)jiggleTTYSizeOnClearBuffer;
 + (BOOL)cmdClickWhenInactiveInvokesSemanticHistory;
 + (BOOL)suppressRestartAnnouncement;
++ (BOOL)showSessionRestoredBanner;
 + (void)setSuppressRestartAnnouncement:(BOOL)value;
 + (BOOL)useAdaptiveFrameRate;
 + (int)adaptiveFrameRateThroughputThreshold;

sources/iTermAdvancedSettingsModel.m

@@ -141,6 +141,7 @@ DEFINE_BOOL(logDrawingPerformance, NO, @"Debugging: Log stats about text drawing
 DEFINE_BOOL(runJobsInServers, YES, @"Session: Enable session restoration.\nSession restoration runs jobs in separate processes. They will survive crashes, force quits, and upgrades.\nYou must restart iTerm2 for this change to take effect.");
 DEFINE_BOOL(killJobsInServersOnQuit, YES, @"Session: User-initiated Quit (⌘Q) of iTerm2 will kill all running jobs.\nApplies only when session restoration is on.");
 DEFINE_SETTABLE_BOOL(suppressRestartAnnouncement, SuppressRestartAnnouncement, NO, @"Session: Suppress the Restart Session offer.\nWhen a sessions terminates, it will offer to restart itself. Turn this on to suppress the offer permanently.");
+DEFINE_BOOL(showSessionRestoredBanner, YES, @"Session: When restoring a session without restoring a running job, draw a banner saying “Session Restored” below the restored contents.");
 #pragma mark - Window
 DEFINE_BOOL(openFileInNewWindows, NO, @"Windows: Open files in new windows, not new tabs.\nThis affects shell scripts opened from Finder, for example.");