added tests for lifelines

tests/lifeline/create-destroy/test.typ

@@ -0,0 +1,32 @@
+#set page(width: auto, height: auto)
+#import "/src/lib.typ": *
+
+#diagram({
+  _par("a", display-name: "Alice")
+  _par("b", display-name: "Bob")
+
+  // Left to right
+  _seq("a", "b", create-dst: true)
+  _seq("a", "b", enable-dst: true)
+  _seq("a", "b", enable-dst: true)
+  _gap()
+  _seq("a", "b", destroy-dst: true)
+  _gap()
+  _seq("a", "b", destroy-dst: true)
+})
+
+#pagebreak()
+
+#diagram({
+  _par("a", display-name: "Alice")
+  _par("b", display-name: "Bob")
+
+  // Right to left
+  _seq("b", "a", create-dst: true)
+  _seq("b", "a", enable-dst: true)
+  _seq("b", "a", enable-dst: true)
+  _gap()
+  _seq("b", "a", destroy-dst: true)
+  _gap()
+  _seq("b", "a", destroy-dst: true)
+})