L3D DASH - Quality Switch on partial segment level

[dsilhavy]

Description

Currently, we do not support a quality switch on partial segment level. Which means we will only switch at the end of a full segment (possibly consisting of multiple partial segments). To support the quality switch on partial segment boundary, we need to carefully check our existing ABR rules. For instance, the BOLA rule maintains its own state of possible representations that now can dynamically change based on partial segments that start with an IDR and partial segments that do not start with an IDR.