MM-52804 - Implement SendPushNotification plugin api method (#24273)

* add SendPushNotification plugin api method

* lint; add testing.Short bc of the sleep

* add interface and generated layers

* add fields to PluginPushNotification; generate mocks

* SendPushNotification -> SendPluginPushNotification; improved comments

* more comments; fix test

* send api.ctx

server/channels/app/plugin_api.go

@@ -1266,3 +1266,31 @@ func (api *PluginAPI) GetUploadSession(uploadID string) (*model.UploadSession, e
 	}
 	return fi, nil
 }
+
+func (api *PluginAPI) SendPluginPushNotification(notification *model.PluginPushNotification) error {
+	var profiles map[string]*model.User
+	var err error
+	if notification.Channel.Type == model.ChannelTypeGroup {
+		if profiles, err = api.app.Srv().Store().User().GetAllProfilesInChannel(api.ctx.Context(), notification.Channel.Id, true); err != nil {
+			return err
+		}
+	}
+
+	sender, appErr := api.app.GetUser(notification.Post.UserId)
+	if appErr != nil {
+		return appErr
+	}
+	user, appErr := api.app.GetUser(notification.UserID)
+	if appErr != nil {
+		return appErr
+	}
+
+	postNotification := &PostNotification{
+		Post:       notification.Post,
+		Channel:    notification.Channel,
+		ProfileMap: profiles,
+		Sender:     sender,
+	}
+	api.app.sendPushNotification(postNotification, user, notification.ExplicitMention, notification.ChannelWideMention, notification.ReplyToThreadType)
+	return nil
+}