Rendering PKI CRL

See https://discuss.hashicorp.com/t/vault-agent-template-get-pki-crl/47672/2

When redering the CRL of a PKI (`{{ with secret "pki-root/cert/crl" }}{{ .Data.certificate }}{{ end }}`), consul-template throws the following error:
```
vault.read(pki-root/cert/crl): failed to check if pki-root/cert/crl is KVv2, assume not: Error making API request.#012#012URL: GET https://active.vault.service.consul:8200/v1/sys/internal/ui/mounts/pki-root/cert/crl#012Code: 403. Errors:#012#012* preflight capability check returned 403, please ensure client’s policies grant access to path “pki-root/cert/crl/”
```

Workaround to suppress this error message:
```
path "pki-root/a-nonexistent-path-so-that-sys-internal-ui-mounts-will-return-info-about-this-mount" {
capabilities = ["list"]
}
```

Proposed solution:
Add some option to force kv version:
`{{ with secret "pki-root/cert/crl" kv_version="1" }}{{ .Data.certificate }}{{ end }}`

No source files or tests are identified in the issue. Start by tracing how the secret template expression for Vault's PKI CRL is parsed and how the pki-root/cert/crl lookup performs its KV-version check; done should include a supported explicit KV-version option that renders the CRL without the 403 preflight error.

Written by the indexing model from the issue text.