Improve reporting on "'too many 5XX error responses"

**Is your feature request related to a problem? Please describe.**
The client classes generated from swaggers perform automatic retries on retriable errors. This is good. However, if the retries don't help, it results in `ResponseError('too many 5xx error responses',)` which gives no further details.
Even with the `--debug` parameter, there are no details given about what the retried errors were.
This is frustrating, as in many cases the actual error returned by the ARM contains useful information which could help even the end user to understand what the problem is.

**Describe the solution you'd like**
It would be helpful if there was some info about what were the errors. Ideally in the form `Last Error: xxxx` which would appear in the output next to the current info. Normally output is given for errors, so why not for these which were retried unsuccessfully.

**Describe alternatives you've considered**
Optionally at least `--debug` could give some more info, though that's not preferable, as it would typically require the user to run the command again to get debug output, which might add round-trip to the support communication.

**Additional context**
This project has many [issues related to too many error responses](https://github.com/Azure/azure-cli/issues?q=is%3Aissue+too+many+error+responses+) (~60 ATM) which all basically show similar pattern of no real resolution/help. Giving more details on the actual error could help many of these cases.