Feature Request

Support for allowing only a certain list of dns names or fingerprints in client certificates

Proposal:

Current behavior:

Only filtering with CA is possible

Desired behavior:

Possible to define
tls_allowed_dns_names = [""]
tls_allowed_fingerprints = [""]

Such that only defines names or fingerprints is allowed to connect to telegraf

Use case:

Locking down access to telegraf even though the CA is shared along with other purposes.
DNS Names allow for a more dynamic approach which fingerprints allow to really pin the certificate down to exactly one.

The code is complete and I can make a PR with it.