Rename color per code review

// FREEBIE

Signal/src/ViewControllers/OWSConversationSettingsViewController.m

@@ -735,7 +735,7 @@ NS_ASSUME_NONNULL_BEGIN
     OWSAssert(icon);
     UIImageView *iconView = [UIImageView new];
     iconView.image = [icon imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];
-    iconView.tintColor = [UIColor ows_blackIconColor];
+    iconView.tintColor = [UIColor ows_darkIconColor];
     iconView.contentMode = UIViewContentModeScaleAspectFit;
     iconView.layer.minificationFilter = kCAFilterTrilinear;
     iconView.layer.magnificationFilter = kCAFilterTrilinear;

SignalMessaging/categories/UIColor+OWS.h

@@ -21,7 +21,7 @@ NS_ASSUME_NONNULL_BEGIN
 @property (class, readonly, nonatomic) UIColor *ows_greenColor;
 @property (class, readonly, nonatomic) UIColor *ows_redColor;
 @property (class, readonly, nonatomic) UIColor *ows_blackColor;
-@property (class, readonly, nonatomic) UIColor *ows_blackIconColor;
+@property (class, readonly, nonatomic) UIColor *ows_darkIconColor;
 @property (class, readonly, nonatomic) UIColor *ows_errorMessageBorderColor;
 @property (class, readonly, nonatomic) UIColor *ows_infoMessageBorderColor;
 @property (class, readonly, nonatomic) UIColor *ows_inputToolbarBackgroundColor;

SignalMessaging/categories/UIColor+OWS.m

@@ -27,7 +27,7 @@ NS_ASSUME_NONNULL_BEGIN
     return [UIColor colorWithRed:8.f / 255.f green:10.f / 255.f blue:0. / 255.f alpha:1.f];
 }
 
-+ (UIColor *)ows_blackIconColor
++ (UIColor *)ows_darkIconColor
 {
     return [UIColor colorWithRGBHex:0x505050];
 }