url-shortener: implements rfd 4 (#65)

* DB Done. Adding new entry in db request Done

* add short url render and redirection

* separate functionality update

* removed global var db

* added two fields in List: owned_id and active?

* fixed minor issues

* db changes

* added NameAlreadyTaken error

* moved address check outside of Create

* changed several minor issues

* chenged opendb func with newsqlitestore
diff --git a/apps/url-shortener/go.mod b/apps/url-shortener/go.mod
new file mode 100644
index 0000000..faf35a8
--- /dev/null
+++ b/apps/url-shortener/go.mod
@@ -0,0 +1,5 @@
+module url-shortener
+
+go 1.21.5
+
+require github.com/mattn/go-sqlite3 v1.14.19 // indirect