1. added tag option to 'get_element_html_by_attribute' function.
this removes the need for using '_search_json'
2. swapped 'if not' statement with 'if' for simplification
feedback: pzhlkj6612
Changes made:
1. AFCVideoIE, CarltonFCVideoIE: fixed the issue to find the correct
video media id. (thanks to pzhlkj6612a)
2. AFCVideoIE: added support for pages where mediaId is unavailable
in webpage
3. CarltonFCVideoIE: split from AFCVideoIE because of point 2 as the
variation is specific to AFCVideo
4. Updated test cases