[WK2] Support multiple URLs for WebApp meta tag

[WK2] Support multiple URLs for WebApp meta tag

[Title] Support multiple URLs for WebApp meta tag
[Issue#] N/A
[Problem] Provide a last icon url only
[Cause]
[Solution] Provide an API to get list of icon data which is the set of icon size and urls for WebApp meta tag
- void (*Ewk_Web_App_Icon_URLs_Get_Callback)(Eina_List *icon_urls, void *user_data) is added.
- Ewk_Web_App_Icon_Data type is added.
Following EAPIs are added
- ewk_view_web_application_icon_urls_get()
- ewk_web_application_icon_data_size_get()
- ewk_web_application_icon_data_url_get()

Change-Id: I51076ddf1fcf9dcb919d9a633a74e13436108c52