Don't close socket if preserveConnection is set in HocuspocusProvider

[douira]

Sending the CloseMessage also has the effect of closing the socket according to its description.

I noticed that before patching this in the package, the socket would be closed when I called destroy on the provider even if it was supposed to preserve the connection. When using multiple providers on the same socket at once, it's important that no provider getting destroyed closes the whole socket. disconnecting the provider is not enough because it still has listeners on the document, socket, and elsewhere which is not acceptable.

[douira]

The test could be fixed by either

• setting preserveConnection to false in the test (it's true by default),
• or changing the default to false,
• or changing how many open connections the test expects,
• or adding a socket.destroy() to the test