add exceptions

From ~/.slk/slk-cli.log, we can derive some more useful exception handling, e.g., let's collect some errocodes here.

SizeMismatchError

Error: Code: 400, Reason: BAD_REQUEST, Message: Size Mismatch, Detailed Message: RCR size: 44894894080 does not match the expected size: 43846318080
2023-04-17 14:57:39 l40002.lvt.dkrz.de 375635 INFO  Non-recursive Archive failed

However, the slk archive command here returend errorcode 1

pyslk.exceptions.PySlkException: pyslk.slk_archive
errorcode: 1
stdout: Non-recursive Archive failed
stderr:

It seems that we can not really distinguish erros from the command returncode.

IOError

Error: Code: 410, Reason: NOT_FOUND, Message: IO Exception, Detailed Message: Namespace not bound to Smart Pool
2023-04-17 15:26:40 l40060.lvt.dkrz.de 332372 INFO  Non-recursive Archive failed 

These errors are not reflected in stderr, so we can not capture it yet. Let's check and print the errorcode in PySlkException. That could give more info than just Non-recursive Archive failed.