libos/LocalServer: Clean up socket file on exit

This doesn't work if the process is killed by an unhandled signal.

libos/include/os/LocalServer.h

@@ -136,6 +136,7 @@ namespace os
         ~LocalServer();
 
       private:
+        StringView m_path;
         int m_fd;
         bool m_blocking;
     };

libos/src/LocalServer.cpp

@@ -43,6 +43,7 @@ namespace os
         fcntl(sockfd, F_SETFD, FD_CLOEXEC);
 
         server->m_fd = sockfd;
+        server->m_path = path;
         return server;
     }
 
@@ -63,6 +64,7 @@ namespace os
     LocalServer::~LocalServer()
     {
         close(m_fd);
+        os::FileSystem::remove(m_path);
     }
 
     LocalServer::Client::Client(Client&& other) : m_fd(other.m_fd)