This commit adds support for handling multiple requests simultaneously by introducing two new functions: `httpd_req_async_handler_begin()` and `httpd_req_async_handler_complete()`. These functions allow creating an asynchronous copy of a request that can be used on a separate thread and marking the asynchronous request as completed, respectively.
Additionally, a new flag `for_async_req` has been added to the `httpd_sess_t` struct to indicate if a socket is being used for an asynchronous request and should not be purged from the LRU cache.
An example have been added to demonstrate the usage of these new functions.
Closes https://github.com/espressif/esp-idf/issues/10594
Signed-off-by: Harshit Malpani <harshit.malpani@espressif.com>
