In #23977 we moved the keyring into Raft, which can expose key material in Raft
snapshots when using the less-secure AEAD keyring instead of KMS. This changeset
adds tools for redacting this material from snapshots:
* The `operator snapshot state` command gains the ability to display key
metadata (only), which respects the `-filter` option.
* The `operator snapshot save` command gains a `-redact` option that removes key
material from the snapshot after it's downloaded.
* A new `operator snapshot redact` command allows removing key material from an
existing snapshot.
Stream snapshot to FSM when restoring from archive
The `RestoreFromArchive` helper decompresses the snapshot archive to a
temporary file before reading it into the FSM. For large snapshots
this performs a lot of disk IO. Stream decompress the snapshot as we
read it, without first writing to a temporary file.
Add bexpr filters to the `RestoreFromArchive` helper.
The operator can pass these as `-filter` arguments to `nomad operator
snapshot state` (and other commands in the future) to include only
desired data when reading the snapshot.
The `nomad operator raft` and `nomad operator snapshot state`
subcommands for inspecting on-disk raft state were hidden and
undocumented. Expose and document these so that advanced operators
have support for these tools.
