Provide more accurate error codes for busy-loop scenarios

[Cyan4973]

In a busy-loop scenario, the user process calls a libzstd streaming function in a loop,
but no work gets ever done, due to some external condition.
For example there is no input to process,
or the output buffer is already full and cannot accept another byte.

These scenarios are considered programming errors. When there is no forward progress, the program can continuously call libzstd in a (potentially infinite) busy loop, cramming away cpu resources and power supply. The caller should not continuously present an empty input (it should wait for some bytes to process), nor an already full destination buffer (it should be flushed first).

To avoid this outcome, libzstd returns an error code after too many function calls with no forward progress happened.

#3454 notes that the corresponding error codes can be difficult to interpret, because they are not specific enough.
This PR adds 2 new error codes, employed specifically for these noForwardProgress scenarios, so that the root cause of the error can be more easily identified.

fixes #3454