Add SLA pausing, SLA reports, SLA filtering and kanban SLA state (phase 3)

Statuses can be flagged to pause the resolution clock; sla_history records the intervals a ticket's clock actually ran and the deadline is re-based on remaining budget when it resumes. Adds SLA Summary and SLA by Client reports, an SLA state filter on the ticket list, SLA colouring on kanban cards, and an Urgent column on the Tickets by Client report. DB update 2.5.1. Also fixes resolution SLA verdicts being skipped when resolving via kanban or the client portal.

db.sql

@@ -2271,6 +2271,21 @@ CREATE TABLE `sla_assignments` (
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;
 /*!40101 SET character_set_client = @saved_cs_client */;
 
+--
+-- Table structure for table `sla_history`
+--
+
+DROP TABLE IF EXISTS `sla_history`;
+CREATE TABLE `sla_history` (
+  `sla_history_id` int(11) NOT NULL AUTO_INCREMENT,
+  `sla_history_started_at` datetime NOT NULL,
+  `sla_history_ended_at` datetime DEFAULT NULL,
+  `sla_history_minutes` int(11) DEFAULT NULL,
+  `sla_history_ticket_id` int(11) NOT NULL,
+  PRIMARY KEY (`sla_history_id`),
+  KEY `sla_history_ticket_id` (`sla_history_ticket_id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;
+
 --
 -- Table structure for table `slas`
 --
@@ -2667,6 +2682,7 @@ CREATE TABLE `ticket_statuses` (
   `ticket_status_name` varchar(200) NOT NULL,
   `ticket_status_color` varchar(200) NOT NULL,
   `ticket_status_active` tinyint(1) NOT NULL DEFAULT 1,
+  `ticket_status_pauses_sla` tinyint(1) NOT NULL DEFAULT 0,
   `ticket_status_order` int(11) NOT NULL DEFAULT 0,
   PRIMARY KEY (`ticket_status_id`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;