tests.connection: add basic encrypted connection tests

Since I went to the effort of getting this to build with LibreSSL, it
makes sense to check that it works. And it seems to. There's nothing
special about the certificates added, except that they don't expire
for 100 years, which is hopefully long enough that nothing will matter
any more. They get baked into the test executable, since this was the
best way I could figure out to be able to consistently load them
during runtime, since they're stored relative to the source, not
necessarily relative to the working directory in use when the test
executable is run.

This required some augmentation to the test server launcher which will
make it easier to add additional flags to it in the future, if that
becomes necessary.

src/connection.zig

@@ -60,7 +60,7 @@ pub const AddressPort = struct {
 };
 
 pub const Connection = opaque {
-    pub fn create(options: *ConnectionOptions) Error!*Connection {
+    pub fn connect(options: *ConnectionOptions) Error!*Connection {
         var self: *Connection = undefined;
         const status = Status.fromInt(nats_c.natsConnection_Connect(@ptrCast(&self), @ptrCast(options)));
         return status.toError() orelse self;