Add iOS trigger repaint method (#3182)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

platform/ios/src/MLNMapView.h

@@ -2121,6 +2121,12 @@ vertically on the map.
 @property (nonatomic) MLNMapDebugMaskOptions debugMask;
 
 - (MLNBackendResource *)backendResource;
+
+/**
+ Triggers a repaint of the map.
+*/
+- (void)triggerRepaint;
+
 @end
 
 NS_ASSUME_NONNULL_END

platform/ios/src/MLNMapView.mm

@@ -7361,7 +7361,12 @@ static void *windowScreenContext = &windowScreenContext;
     return _annotationViewReuseQueueByIdentifier[identifier];
 }
 
-- (MLNBackendResource*)backendResource {
+- (void)triggerRepaint
+{
+    _mbglMap->triggerRepaint();
+}
+
+- (MLNBackendResource *)backendResource {
     return _mbglView->getObject();
 }
 
@@ -7526,4 +7531,6 @@ static void *windowScreenContext = &windowScreenContext;
     self.showsUserHeadingIndicator = showsHeading;
 }
 
+
+
 @end