Retry send records after auth exception

[erikvanoosten]

Some brokers are sometimes too slow to authorize or authenticate a send. This results in spurious exceptions. With this change we retry sends unless the error happens too often.

Still todo:

• make it a bit more efficient for the success case (e.g. only create schedule driver when necessary)
• make retry setup more efficient (loop through only once to collect firstAuthError, authErrorCount and errorCount
• add tests
• fix comment typo firs auth error => first auth error