Add provisionerName to webhook request for x509 and SSH

[Yannik]

Name of feature:

Add provisionerName to webhook request for x509 and SSH

Pain or issue this feature alleviates:

The provisionerName field in RequestBody (webhook/types.go:86) is only populated for SCEP webhooks (authority/provisioner/scep.go:160). For X509 and SSH webhooks, the field is always empty despite the provisioner being available as a parameter in all four call sites (callEnrichingWebhooksX509, callAuthorizingWebhooksX509, callEnrichingWebhooksSSH, callAuthorizingWebhooksSSH). This makes it impossible for webhook servers to implement per-provisioner logic (e.g., enforcing different key policies for different ACME provisioners).

Why is this important to the project (if not answered above):

The field already exists in the struct and is documented as part of the webhook request body. Not populating it for X509/SSH breaks the reasonable expectation that all webhook types provide the same base context to webhook servers.

Is there documentation on how to use this feature? If so, where?

The webhook request body is documented at https://smallstep.com/docs/step-ca/webhooks/ but does not currently mention provisionerName. The field exists in the RequestBody struct (webhook/types.go:86) and is already populated for SCEP webhooks, but is undocumented.

In what environments or workflows is this feature supported?

All provisioner types that trigger X509 or SSH enriching/authorizing webhooks (ACME, JWK, OIDC, x5c, etc.). SCEP already works and is unchanged.

[CLAassistant]

All committers have signed the CLA.

[maraino]

Thanks @Yannik, in PR #2631 I've changed the way to add the provisioner name is added using a new method RequestBodyOption, webhook.WithProvisionerName(prov). And merge that version, it also includes your commits.