Further approach for measurement and estimation of throughput calculation in LL CTE streaming

[mlasak]

Adding a further approach for measurement and estimation (FAME) for chunked transfer encoding based streaming.

Implemented concepts:

• Make use of availabilityStartTime to decide if segment is downloaded at network speed or at producer rate
• Make use of availabilityStartTime to decide which chunks are downloaded at network speed or at producer rate
• Keep track of the timings of recent chunk download timings (last segments)

This fixes, e.g.
#3538

This PR adds a new kind of needed test: unit tests in browser scope. This is necessary as some API (e.g. fetch API) is not available in node.js context.

• add config parameter to reference player
• further tests, all possible patterns
• more documentation (update: added sample page)
• decide if concept of artificial delays (to enforce some chunks to be downloaded at network speed) should be added (update: discussed approach during monthly call)