[keylime] Add plugin for Keylime remote attestation

[suraj-cmd]

Keylime is packaged for Fedora and RHEL and provides TPM-based remote
attestation, but sos has no plugin for it and no other plugin references it. An
sosreport from a verifier, registrar or agent host currently contains none of
its configuration or service state.

The paths and unit names are taken from the upstream packaging:
services/keylime-tmpfiles.conf creates /etc/keylime with the per-component
.conf.d drop-in directories and /var/lib/keylime at mode 0700, and the
units are keylime_agent, keylime_registrar and keylime_verifier.

/var/lib/keylime is deliberately not copied. keylime/ca_util.py writes the
deployment CA key there as <name>-private.pem, and the same tree holds
decrypted payloads. A recursive listing is taken instead, which still shows the
CA state and file ownership. PEM files are added to the forbidden paths so no
key material can be collected from either location.

Paths and unit names come from upstream services/keylime-tmpfiles.conf and
docs/man/ rather than a running deployment, so confirmation against a
packaged install would be welcome — particularly whether the distribution
packages split the config differently.

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[packit-as-a-service]

Congratulations! One of the builds has completed. 🍾

You can install the built RPMs by following these steps:

• sudo dnf install -y 'dnf*-command(copr)'
• dnf copr enable packit/sosreport-sos-4423
• And now you can install the packages.

Please note that the RPMs should be used only in a testing environment.