This refactoring was pulled out of https://github.com/home-assistant/core/pull/53676 as an
initial step towards reverting the addition of the SegmentBuffer class, which will be
unrolled back into a for loop.
The StreamState class holds the persistent state in stream that is used across stream worker
instantiations, e.g. state across a retry or url expiration, which primarily handles
discontinuities. By itself, this PR is not a large win until follow up PRs further simplify
the SegmentBuffer class.
8ca89b10eb