Ability to upload files to an approved quote

[wrongecho]

Allows clients to upload files (likely purchase orders) attached to quotes. *Files are uploaded into the standard file viewer, but just linked to the quote.

Draft for now, will add db.sql and database updates once we've merged #1158.

I still don't entirely like the placement of the approve/decline and now upload buttons. They're cut off on a 13" laptop screen unless you zoom out. But one for later.

Client - guest_view_quote.php

Admin - quote.php

---

UPDATE:

mysqli_query($mysqli, "CREATE TABLE `quote_files` (
	`quote_id` INT(11) NOT NULL,
	`file_id` INT(11) NOT NULL,
	PRIMARY KEY (`quote_id`, `file_id`))
)");

DB.SQL

--
-- Table structure for table `quote_files`
--

DROP TABLE IF EXISTS `quote_files`;
/*!40101 SET @saved_cs_client     = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `quote_files` (
  `quote_id` int(11) NOT NULL,
  `file_id` int(11) NOT NULL,
  PRIMARY KEY (`quote_id`,`file_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
/*!40101 SET character_set_client = @saved_cs_client */;

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[johnnyq]

@wrongecho I pulled in @ssteeltm Kanban pull. This is pull is ready for the DB update