Add WiFiWebClient example

[pennam]

This PR is a work in progress.

Some configs to enable debug:

CONFIG_NET_LOG=y
CONFIG_NET_L2_WIFI_MGMT_LOG_LEVEL_DBG=y
CONFIG_WIFI_LOG_LEVEL_DBG=y

Can happen that connection fails due to:

<err> esp_hosted: failed to receive response for 206

Increasing ESP_HOSTED_SYNC_TIMEOUT does not help. Adding a delay(100) in WiFi.begin() before return status() works, but there should be a better solution.

Probably we should wait until NET_EVENT_IPV4_ADDR_ADD.

Disabling debug prints makes connection even less reliable.