Improve CLI HTTP error messages

[mozzieongit]

Originally, we often just printed the debug output of errors. That is very confusing and noisy. This PR changes that to chaining together the human-readable error descriptions of nested errors (relevant e.g. for tcp connection errors).

Example errors:

2026... ERROR cascade: Error: HTTP response decoding failed: expected value at line 1 column 1
2026... ERROR cascade: Error: HTTP connection failed: client error (Connect): tcp connect error: Connection refused (os error 111)
2026... ERROR cascade: Error: HTTP connection timed out
2026... ERROR cascade: Error: HTTP request failed: client error (SendRequest): connection closed before message completed

Fixes: #481