Add --output/-o to secrets-encrypt status

[jakefhyde]

Proposed Changes

Add secrets-encrypt status -o/--output.

Given that the k3s docs were not updated for this change (and I couldn't find any open associated issues or PRs), I don't believe so

Types of Changes

Add cli flag

Verification

Can be verified the same was as it was for k3s: k3s-io/k3s#5138 (comment). I verified it myself by provisioning a cluster with rke2 version v1.23.4+rke2r2:

root@jhyde-rke2-test-pool1-444c534f-rc96x:/tmp# ./rke2-test secrets-encrypt status
Encryption Status: Enabled
Current Rotation Stage: start
Server Encryption Hashes: All hashes match

Active  Key Type  Name
------  --------  ----
 *      AES-CBC   aescbckey

root@jhyde-rke2-test-pool1-444c534f-rc96x:/tmp# ./rke2-test secrets-encrypt status -o json
{
        "stage": "start",
        "activekey": "aescbckey",
        "enable": true,
        "hashmatch": true
}

Linked Issues

#2680

Further Comments

I'd considered exposing the flag from k3s in the event that k3s supports different formats at some point, but the overhead for creating PRs for rke2 in that case to update the help text would be extremely low anyways.