…ane Versioned and Versionless Key IDs

…ssignment

This switches to using the Resource ID the Resource actually uses rather than this apparent Terraform unique value?

This now uses `managed_hsm_id` to discover the Managed HSM rather than the Data Plane URI - which mirrors the pattern used elsewhere.
This is important for two reasons:

1. We don't support provisioning resources across Subscriptions - a unique Provider instance needs to be used for each Subscription
2. This allows us to determine when the Managed HSM in question has been removed out-of-band due to limitations in Go's networking layer

…he Parse function directly

This was tested via the validate, but was missing tests covering this directly

…leanup

…gnment IDs

This causes "/" to become "", and "/keys" to become "keys"

We only trim the first leading slash when parsing, not when outputting.

…ignments