Feature: offline_log_viewer updates

[andijcr]

trafficstars

Cover letter

These changes add a first support in tools/offlile_log_viewer for serde-encoded controller messages.

running

python viewer.py --type controller --path [redpanda data path]

will decode logs produced by v22.2 and earlier. serde commands start with a field 'envelope' that contains [version, compat_version, encoded_size].

Partially fixes #5293,

implements:

• [x] serde decode of controller commands:
  • [x] decode_topic_command
  • [x] decode_user_command
  • [x] decode_acl_command
  • [x] decode_config_command
  • [x] decode_feature_command
  • [x] decode_node_management
• [ ] gold master and coverage testing
• [ ] ductape integration
  • [ ] test that new version of redpanda can be completely decoded with this tool
  • [ ] add means to run this tool as a part of a ductape test

open questions:

• should there be a check (with a message) that all the bytes are processed?
• should the structure of the json reflect more closely the cpp class hierarchies (some hierarchies are flattened)?
• should the names of the fields match the one used in the cpp source (some names are abbreviated or de-abbreviated)?

Backport Required

• [ ] not a bug fix
• [ ] issue does not exist in previous branches
• [x] papercut/not impactful enough to backport
• [ ] v22.2.x
• [ ] v22.1.x
• [ ] v21.11.x

UX changes

messages are decoded in a stream of json files. the schema for adl encoded files is unchanged, but the schema for serde - encoded message is different in some places than the corresponding adl-one, reflecting more the hierarchical data organization.

Release notes

• none

[CLAassistant]

All committers have signed the CLA.

[jcsp]

@andijcr can you merge https://github.com/redpanda-data/redpanda/pull/5315 into this branch as a starting point for tests? I just rebased that PR but I expect it to fail without the changes in this PR to add serde support.

[jcsp]

(didn't review the code but I notice the commit messages aren't in the usual format: see CONTRIBUTING.md in the source and/or take a peek at the commit history)

[jcsp]

@andijcr this has been stalled for a while -- it's not our top priority, but it would be good to know if there were issues blocking this

[jcsp]

I've merged this into https://github.com/redpanda-data/redpanda/pull/5315