added tests for lifelines

tests/lifeline/event/test.typ

@@ -0,0 +1,40 @@
+#set page(width: auto, height: auto)
+#import "/src/lib.typ": *
+
+#diagram({
+  _par("a", display-name: "Alice")
+  _par("b", display-name: "Bob")
+
+  _evt("a", "enable")
+  _gap()
+  _seq("a", "b")
+  _evt("a", "disable")
+  _gap()
+  _evt("a", "enable")
+  _evt("b", "enable")
+  _seq("a", "b")
+  _evt("a", "enable")
+  _evt("b", "enable")
+  _gap()
+  _seq("a", "b")
+  _evt("a", "disable")
+  _evt("b", "disable")
+  _gap()
+  _evt("a", "disable")
+  _evt("b", "disable")
+})
+
+#pagebreak()
+
+#diagram({
+  _par("a", display-name: "Alice")
+  _par("b", display-name: "Bob")
+  _par("c", display-name: "Charlie")
+  
+  _seq("a", "b")
+  _gap()
+  _seq("a", "b", enable-dst: true)
+  _evt("c", "create")
+  _seq("c", "a")
+  _evt("b", "destroy")
+})