Update XSL package (#9015)

This commit...

1. transfers "XSL" package to https://github.com/SublimeText/XSL
2. merges "XSLT Snippets" package into "XSL".

Despite its name "XSLT Snippets" provides also syntax definition,
completions and symbol list definitions.

XSL was primarily intended as backward compatibility package as
ST3083 dropped that syntax from core packages. It defines same
main scope `text.xml.xsl` as syntax from "XSLT Snippets".

For ST4 XSL packages now provides rewritten syntax for XSL(T)
and XSD with full support for XPath and RegExp highlighting.

repository/x.json

@@ -236,23 +236,21 @@
 		},
 		{
 			"name": "XSL",
-			"details": "https://github.com/packagecontrol/XSL",
-			"labels": ["language syntax"],
+			"details": "https://github.com/SublimeText/XSL",
+			"labels": ["language syntax", "snippets"],
+			"previous_names": ["XSLT Snippets"],
 			"releases": [
 				{
-					"sublime_text": ">3083",
-					"tags": true
-				}
-			]
-		},
-		{
-			"name": "XSLT Snippets",
-			"details": "https://github.com/hoest/SublimeXSLT",
-			"labels": ["snippets"],
-			"releases": [
+					"sublime_text": "3083 - 4106",
+					"tags": "st3-"
+				},
 				{
-					"sublime_text": "*",
-					"branch": "master"
+					"sublime_text": "4107 - 4125",
+					"tags": "4107-"
+				},
+				{
+					"sublime_text": ">=4126",
+					"tags": "4126-"
 				}
 			]
 		},