* Support vault namespaces in connect CA
Follow on to some missed items from #12655
From an internal ticket "Support standard "Vault namespace in the
path" semantics for Connect Vault CA Provider"
Vault allows the namespace to be specified as a prefix in the path of
a PKI definition, but our usage of the Vault API includes calls that
don't support a namespaced key. In particular the sys.* family of
calls simply appends the key, instead of prefixing the namespace in
front of the path.
Unfortunately it is difficult to reliably parse a path with a
namespace; only vault knows what namespaces are present, and the '/'
separator can be inside a key name, as well as separating path
elements. This is in use in the wild; for example
'dc1/intermediate-key' is a relatively common naming schema.
Instead we add two new fields: RootPKINamespace and
IntermediatePKINamespace, which are the absolute namespace paths
'prefixed' in front of the respective PKI Paths.
Signed-off-by: Mark Anderson <manderson@hashicorp.com>