refactor: change event lib minimal examples to serve as the test apps

CMakeLists.txt

lib/context.c

lib/event-libs/README.md

lib/event-libs/libev/libev.c

lib/event-libs/libev/private.h

lib/event-libs/libevent/libevent.c

lib/event-libs/libevent/private.h

lib/event-libs/libuv/private.h

lib/event-libs/private.h

lib/libwebsockets.c

lib/libwebsockets.h

lib/plat/lws-plat-unix.c

lib/private-libwebsockets.h

lib/roles/README.md

lib/roles/h1/ops-h1.c

lib/roles/h2/ops-h2.c

lib/roles/http/client/client-handshake.c

lib/roles/http/client/client.c

lib/roles/http/server/server.c

lib/roles/private.h