Tested under ESP32S3, running 50 tasks, each with a client, and a server
listening to one client, totalizing 150 sockets/files open, forwarding
data from PPP to Ethernet and vice versa.
Reasoning for 255 total sockets/files is VFS local_fd_t being a uint8_t.
Since FD_SETSIZE is defined at tool level, a CMakeLists user definition
is needed in cases above 64 (the default value).
Merges https://github.com/espressif/esp-idf/pull/13866