Content Steering - v1.1.1 support

[dsilhavy]

Description

dash.js implements version 0.9.7 of the content steering specification. Significant changes were done in version 1.1.1 of the specification as published here: https://www.etsi.org/deliver/etsi_ts/103900_103999/103998/01.01.01_60/ts_103998v010101p.pdf

Tasks

1. Identify the delta between the current implementation and the latest version of the Content Steering specification
2. Implement the required changes