Kafkacrypto

This fixes a couple of high priority bugs:
- Improper configuration loading due to case-insensitive keys in ConfigParser. This has been resolved by properly implementing case-insensitive checks while retaining file case sensitivity for proper base64 operation in keys.
- Fix a bug where a combined producer and consumer would respond to its own consumers key requests. Reworked implementation to only respond when the key index requested is available.

This is 0.9.8, with one fix to the kafka-python wrapper code that was missed in the original release.

This release continues to make changes based on security reviews. Major change is a revamp of the chain processing code to be more readable and enable future additions to be made more easily. Major changes include:
1. Implementation of allowlist and denylists. This removes the need for separate code pathways for root of trusts, enabling them to be treated as entries in allowlist.
1. Implementation of automatic processing of messages to adjust allowlists, denylists, and chains. This enables very short chain lifetimes, a security benefit. It also enables a private key to self-sign that it should be revoked.
1. Implementation of a pathlength constraint for further tightening of chains. Minimum usable value is typically 1, unless the end of the chain will not sign any further messages.
1. Fix kafka wrapper poll implementation to make the timeout optional.

Resolve bug where Controller would crash if enable_auto_commit was not set.

Refactor to make all non-private-key material in text configuration files.

This release fixes several bugs related to the portability wrapper between kafka-python and confluent_kafka.

One low severity security fix identified during the crypto review also resolved.

Fix for minor cryptokey bugs, and make file loading more robust.