lang: core: net: Add a new func for URL parsing

This is a first attempt to add a new function for URL parsing, using
go's net/url package and the simple API. This is still a barebones
implementation, there's possibility to expose more information. It also
includes simple tests.

lang/interpret_test/TestAstFunc2/url_parser.txtar

@@ -0,0 +1,22 @@
+-- main.mcl --
+
+import "net"
+import "fmt"
+
+$url1 = "https://www.example.com/search?q=mgmt"
+$url2 = "ftp://example.com/apath"
+$url3 = "https://www3.weird.url/?qu=ery"
+
+$url_parse1 = net.url_parser($url1)
+$url_parse2 = net.url_parser($url2)
+$url_parse3 = net.url_parser($url3)
+
+test [fmt.printf("%s %s %s %s", $url_parse1->scheme, $url_parse1->host, $url_parse1->path, $url_parse1->raw_query),] {}
+test [fmt.printf("%s %s %s %s", $url_parse2->scheme, $url_parse2->host, $url_parse2->path, $url_parse2->raw_query),] {}
+test [fmt.printf("%s %s %s %s", $url_parse3->scheme, $url_parse3->host, $url_parse3->path, $url_parse3->raw_query),] {}
+
+-- OUTPUT --
+
+Vertex: test[https www.example.com /search q=mgmt]
+Vertex: test[ftp example.com /apath ]
+Vertex: test[https www3.weird.url / qu=ery]