Convert all tests to single-file packages.

tests/vibe.core.net.1452.d

@@ -0,0 +1,30 @@
+/++ dub.sdl:
+name "test"
+description "Invalid memory operation on TCP connection leakage at shutdown"
+dependency "vibe-core" path="../../"
++/
+module test;
+
+import vibe.core.core;
+import vibe.core.net;
+import core.time : msecs;
+
+class C {
+	TCPConnection m_conn;
+
+	this()
+	{
+		m_conn = connectTCP("example.com", 443);
+	}
+
+	~this()
+	{
+		m_conn.close();
+	}
+}
+
+void main()
+{
+	auto c = new C;
+	// let druntime collect c during shutdown
+}