Re-evaluate ssh authorization decision on a fixed interval, or whenever
the config changes. If access is no longer allowed, log a new 'authorize
check' message and disconnect.
Refactor the ssh.StreamManager initialization so that its lifecycle
matches the Authorize lifecycle.
Implement the pkg/ssh.AuthInterface. Add logic for converting from the
ssh stream state to an evaluator request, and for interpreting the
results of policy evaluation. Refactor some of the existing authorize
logic to make it easier to reuse.
## Summary
This implements the StreamManagement API defined at
https://github.com/pomerium/envoy-custom/blob/main/api/extensions/filters/network/ssh/ssh.proto#L46-L60.
Policy evaluation and authorization logic is stubbed out here, and
implemented in https://github.com/pomerium/pomerium/pull/5665.
## Related issues
<!-- For example...
- #159
-->
## User Explanation
<!-- How would you explain this change to the user? If this
change doesn't create any user-facing changes, you can leave
this blank. If filled out, add the `docs` label -->
## Checklist
- [ ] reference any related issues
- [ ] updated unit tests
- [ ] add appropriate label (`enhancement`, `bug`, `breaking`,
`dependencies`, `ci`)
- [ ] ready for review
## Summary
Adds the envoy listener config logic for ssh.
## Related issues
<!-- For example...
- #159
-->
## User Explanation
<!-- How would you explain this change to the user? If this
change doesn't create any user-facing changes, you can leave
this blank. If filled out, add the `docs` label -->
## Checklist
- [ ] reference any related issues
- [ ] updated unit tests
- [ ] add appropriate label (`enhancement`, `bug`, `breaking`,
`dependencies`, `ci`)
- [ ] ready for review
