Update to Exceptions: add codes, update phpunit tests

DB Class throws Exception if on init it fails to connect to the DB,
will not throw Exception if failed connection during execution but
will do the normal retry and soft failure run
DB\ArrayIO will throw Exception on missing table array and table name

All Exceptions have a code set

4dev/tests/Check/CoreLibsCheckColorsTest.php

@@ -13,6 +13,11 @@ use PHPUnit\Framework\TestCase;
  */
 final class CoreLibsCheckColorsTest extends TestCase
 {
+	/**
+	 * Undocumented function
+	 *
+	 * @return array<mixed>
+	 */
 	public function validateColorProvider(): array
 	{
 		/*