Add wrapper for HTTP

[kevinhikaruevans]

• Create structs http_message with two smaller structs: request and response
• Consider somehow buffering the response body or implementing some reasonable IO paradigm going to have an independent buffer per socket
• DNS lookups and possibly caching on device? Is there a std MRU cache I could use here? DNSs can be handled transparently by the ESP32 by using the fqdn in the AT+CIPSTART command
• determine if DNS lookups are required or if they're handled transparently by AT+CIPSTART
• check out how https://github.com/SharpCoder/esp8266-arduino/ is handling the AT commands (thanks Josh!)
• refactor callbacks, maybe use return true/false when the request is done vs not done; add funct to check if OK/ERROR is sent or an enum?
• add method of transactions, i.e. if sending multiple commands, if one command fails, it can return/fallback will do in the future
• consider adding TCP handler and having HTTP implement that wrapper