Fix and document changing sensitive properties algorithm

[maltesander]

Description

fixes #791

• move sensitive properties CRD to own module
• check for deprecated algorithms in NiFi 1.x.x and emit warning
• check for unsupported algorithms in NiFi 2.x.x and error out if used
• fix setting nifi.flow.configuration.json.file in NiFi 1.x.x which stopped CLI tools from working
• documented step by step how to update the algorithms

Test script with a couple of commands:
test-nifi-sensitive-properties.sh.tar.gz

Definition of Done Checklist

• Not all of these items are applicable to all PRs, the author should update this template to only leave the boxes in that are relevant
• Please make sure all these things are done and tick the boxes

Author

• Changes are OpenShift compatible
• CRD changes approved
• CRD documentation for all fields, following the style guide.
• Helm chart can be installed and deployed operator works
• Integration tests passed (for non trivial changes)
• Changes need to be "offline" compatible

Reviewer

• Code contains useful comments
• Code contains useful logging statements
• (Integration-)Test cases added
• Documentation added or updated. Follows the style guide.
• Changelog updated
• Cargo.toml only contains references to git tags (not specific commits or branches)

Acceptance

• Feature Tracker has been updated
• Proper release label has been added
• Roadmap has been updated