Proposal to include this library as part of the arduino-esp32 core

[Zhu-jiatong]

This library is much more powerful and versatile as compared to the WebServer library in the current arduino-esp32 core. Since there are plans to include the AsyncTCP into the arduino-esp32 core, it would also be nice if this library could also be included. This could grant the library better continuous support. It is important to acknowledge that this is not to suggest the immediate removal of the WebServer library. Rather, this proposal aims to provide users with a better-supported alternative, and give existing users of ESPAsyncWebServer an always up-to-date library.