Geearl/5872 fr internal error

[georearl]

This PR covers tickets 5872, 5874, 5877, 5873 and 5880. The functionality introduced includes:

• working around internal errors we encounter in FR when it is at capacity
• fixed skipped file types registering as errors
• moved all backoff and retry variables to configuration settings
• changed logging so it only writes out to cosmos after the completion of the function with all status updates, not on every status update. This will reduce the amount of write calls by about 10:1, and therefore reduce the chances of throttling and cost
• documentation of known issues around throttling and internal errors plus how to override the backoff and retry settings for development purposes