The task that runs the HTTP server can now be pinned to a particular core by setting `core_id`
in the HTTP server configuration. By default, the core is set to `tskNO_AFFINITY`, meaning
it can run on any core.
Merges https://github.com/espressif/esp-idf/pull/3190
transport_mode accepts enum httpd_ssl_transport_t instead of true/false.
This will allow for extension to dual mode (server running on both secure and insecure ports) in the future.