ui:Add flash notify for email preference seting success (#11027)

* Add flash notify for email preference seting success

Signed-off-by: a1012112796 <1012112796@qq.com>

* add review suggest changes

Co-authored-by: Lauris BH <lauris@nix.lv>

Co-Authored-By: Lauris BH <lauris@nix.lv>

Co-authored-by: Lauris BH <lauris@nix.lv>

options/locale/locale_en-US.ini

@@ -460,6 +460,7 @@ add_email = Add Email Address
 add_openid = Add OpenID URI
 add_email_confirmation_sent = A confirmation email has been sent to '%s'. Please check your inbox within the next %s to confirm your email address.
 add_email_success = The new email address has been added.
+email_preference_set_success = Email preference has been set successfully.
 add_openid_success = The new OpenID address has been added.
 keep_email_private = Hide Email Address
 keep_email_private_popup = Your email address will be hidden from other users.

routers/user/setting/account.go

@@ -149,6 +149,7 @@ func EmailPost(ctx *context.Context, form auth.AddEmailForm) {
 			return
 		}
 		log.Trace("Email notifications preference made %s: %s", preference, ctx.User.Name)
+		ctx.Flash.Success(ctx.Tr("settings.email_preference_set_success"))
 		ctx.Redirect(setting.AppSubURL + "/user/settings/account")
 		return
 	}